If this is true then I think you should probably send out a nice letter to your customers and tell them that your refunding their money because Google is causing you grief, link to a blog post explaining the situation in details, and ask them to pay again via your new merchant provider. I think that if people saw the refund on their statement, then they'd pay again. Then you'd get something.
I think the lesson here is that you should never rely on a service / company who won't put any effort into customer support. I thought this was common sense?