sometimes the easiest way to collect on a funded milestone is to ignore them once you've sent the payment request. If you don't have a revision request pending, then you get the money after two weeks. By hounding the customer, you're opening yourself up to having a revision request sent again even if there isn't anything more to do. My policy is that I'll do one set of revisions no questions asked. The second one, you'd better have a good reason. Third one? Uh, nope.