Emer Jones Apparel
I initially had issues when installing the app, but the support I have to say have been great and they've really wanted to help to fix the issues.
They are in the process of fixing one last issue caused by Shopify.
This is literally the ONLY app for google merch center, the shopify app only allows US based companies. These guys work with google to bring us this app.
So if you have any issues at all, contact them. It was much easier to contact them via skype than email as this helped with any confusion over emails.
If you have any issues, contact support and they WILL help!