I’m really surprised your CU uses a paper check to forward your payment to GMAC. I’ll rephrase that. That is BS. I take you at your word that you were told that, but I would suspect that is some goofball story told you by a bank clerk. This is not 1993.
You need to get above the “clerk” level at your CU and get to a manager, get them to write a letter on letterhead that those payments were made and were made timely. Certainly, you have a ckg acct statement showing those exact amounts. I assume they are unique amounts with cents in the payment, eg; not $330.00 but $331.28 that are immediately identifiable and unique; and that prior payments of that precise amount were made on time and that you ckg acct never sank below a minimum balance where those amounts could not be paid without an NSF. Most banks show a “minimum daily balance” on their stmts.
If the false credit report actually dings your report and makes you ineligible for a refi THAT YOU WERE IN PROGRESS FOR when the ding dinged you, that is quite potentially actionable. You will need a letter from the lender stating you can’t get “that” loan any more.
I doubt you’ll be able to find an attorney to take this without a substantial retainer, but a 1% difference on a $150K refi is over $23K in interest over 30 years. That ain’t chopped liver.
It is a smaller credit union in my area. They did confirm the check was a cut check that is mailed to GM Finance. I will certainly be stopping by the branch tomorrow for said letter. My interest rate is such that it wouldn’t be worth it to refinance because I wouldn’t be able to take advantage of the lower rates available.
I was patient to a point with GM but now all bets are off.