Installed but shown error, tried to contact support, but email and phone can't get though, don't know if this app still available

We lost many sales orders due to this app freezing our checkout for a few days. We had to press their support 2 seperate times over 2 days in order for them to admit the problem that their app uses localStorage to store their info and then deletes everything from that shared localStorage, even data used by other apps. This is a huge problem that needs to get fixed asap. Also, their server "shinedezign" url shows up in your browsers status bar when the shopping cart accesses the app. This can also be a problem for cusotmers who might think their financial transaction is getting hacked: imagine shopping online and seeing some random URL show up during a purchase. I'll update this review as soon as they update me on the status of these huge issues.

Unfortunately the app caused problems with my website, my mega menu stopped working, the add to cart button also wasn't there, the developers were trying to help but unfortunately with different issues over 3 days it was not worth continuing with the app, I deleted the app initially within 8 hours of installing and opting for the higher level, then reinstalled the free version so developers could try and fix the problems and was charged $17.99 NOT IMPRESSED

It hides my Add-to-cart button on Product Page and doesn't work with other apps. And we pay the best plan, was a total disappointed

It hides my Add-to-cart button on Product Page,
I deleted this App immediately once I received the call from my customer who can't buy the product he wanted.
But it still hiding my Add-To-Cart and now I need to contact my web developer to clear all leftover codes.
I hope the App developer di the testing first before quietly updating from the background next time.

Just the app I was looking for. I wanted an app with partial payment which other preorder apps don't have. Setup is a bit confusing and not as simple and straightforward but Ritika and Vikas were very helpful and even took suggestions on certain parts. There's still some areas that need improvement but I'm sure they will get to it soon. This time all the products were preorder items so I didn't encounter any issues but one of the reviews below say that the app doesn't work if non-preorder items are added to cart - that's a bit worrisome so I hope it's fixed.
UPDATE: I have a lot of gripes with this app - from the app functions to the abysmal customer support.
Firstly, the discount box disappeared and only appears at certain times. Customers are also unable to use discount(Ultimate Special Offers) coupon for partial payment preorders. So I emailed support 2-3 days back and they got back to me quickly at first but now Vipin Garg has apparently/conveniently forgotten all about it. This is not the first time they just dropped all communication in the middle.
Secondly, my problem was that the customer was able to place a preorder today even though I disabled the preorder function and hid the products on the site yesterday. The products are hidden and therefore not visible on the site so obviously any person with brain cells can deduce that there must be some other factor that's enabling the customer to place the pre-order. It's only logical to arrive at the conclusion that the most likely culprit is The Advanced Preorder app because guess what? It is THE ONLY PREORDER APP I have. Instead of trying to help me figure what the issue might be, Ritika just won't acknowledge that the problem might be because of some bug or whatever within the app. She said it's not the app's fault that the customer was able to place a pre-order
USING THE APP LOL As of writing this, Ritika has disconnected the chat because she apparently can't wait for 2 minutes for me to respond back.
At this point, it's not even the app issues because as long as support is at least willing and trying to help, those issues can be overlooked.

APP DEVELOPER REFUSED REFUND!!! BEWARE!!! - Had lots of issues with the app not working from the install. App Support was only able to solve a few issues... this product is half baked. - Issues with badge covering navigation menu, also covering product names in mobile, and covers functions of the cart tray
- Does not work with Shopify Cart Tray
- Does not respect the requirement for Customer checking the box for Terms and Conditions
- Missing Cart Images, App developer blamed Shopify Draft Order API for not allowing them to get the images
- Incorrect text (vendor sku instead of product name) shown next to the Item in the shopping cart due when using the app
- Does not work when adding more than one item to the cart, especially if the other item is not a preorder item

I installed this app and paid for the premium version with support. The only support option is to email within the app, and all I get is "email cannot be sent"

Super frustrating.

The app was not working properly, and didn't remove the buy now button. It just shows both pre-order and buy now buttons next to each other.

we involved Shopify but the problem didn't resolve and we had many frustrated customers and tens of complaints.

Really bad experience!!

The app worked well for a few days.
Then their server seems to have stopped working. My site is totally blocked (it load a page in 55 seconds).