I recieved an offer of a credit card while being a little aliquorated.
I was bored and filled out.
When I read the terms next morning, I called and forcefully cancelled it.
Threating them with usury against an unstable senior citizen. Two aggravants.
They promised to ruin my credit. I promised to sue them.
At the end of like an hour fighting, they cancelled the dam card. Still not giving warranty
that they won't touch my credit. They never did. They know better that fighting with a crazy old man.

In your case, money exchanged hands. I'm alien to that situation.
My advice would be to make an appointment with a lawyer.
99% of the time, the first consultation is a freeby.

Good luck. Cheers.