Hi Mavis,
What does your contract with GMAC say about default payments?
What does the contract allow GMAC to do as far as liquidating the asset..?
That's where I would start..
If your car was repossessed in Nov, that means you must not have made payments for several months prior to that... when was your last payment?
You paid the $1290 within the 21 days? Did you get a receipt or something in writing?
did you have a bad credit car loan?

