Signifyd

Wrongly turned off store syncing without our permission.
Was advised it was because we didn't use the service, but upon further checking we did have it turned on and using it.

Asked support to restore it and fix syncing transactions for guarantee, and they advised they did, but still not working.

Really great service. The support team is quick to respond to any inquiry.
The platform itself is relatively easy to set up and has significantly helped to prevent fraud on out site. In addition, we use Signifyd to fight chargebacks which has freed up our time. Their order guarantee is an added plus. Highly recommend.

Interface is relatively simple to use. Unfortunately when you need them don't expect them to be there for you. We've been a customer of Signifyd since the app was new and have never filed for a chargeback claim reimbursement. We've used the guarantee for only orders that were concerning to us ('pay as you go' plan), but even those that were guaranteed never went to a claim so our account has been pure profit for them.
We just found out that they decided to stop supporting the plan that we have been on and closed our account. They didn't send any notification that the account was going to be closed nor that it was closed, and no way to get it back without a $500 monthly minimum spend. Apparently small businesses aren't worth their time.

Simply the best in class for chargeback protection and support.

Just a great service. We started with the on-demand plan, and recently upgraded to the "Complete" plan. They've come through for us on every chargeback, although though we don't get very many. We can't compare it to other such services, since we haven't ever used such before, but they're great, and stellar customer support too (Tony being a standout).