Okay by now you realize you were lied to by Transit Pro LLC.
They induced you to buy the tires by committing a fraud.
Stating "they insisted to charge my credit card over the phone, with the price quoted from Good Sams National Contract".
As you probably realize now there is no national contract with GSRA to buy tires mentioned in any of the brochures that Good Sam uses in place of a contract.
You were lied to by the service company and I would protest the charges on my card as you were not aware of the fraud when it was committed. The credit card company may well charge back the amount to the company and they will not get paid
Next I would snail mail the attorney general of Utah as well as the DMV and see what they can do.It may not help but maybe enough complaints and they may take action.
Then I would mail GSRA AT
Roadside Assistance
P.O. Box 6888,
Englewood, CO 80155-6888 via something with a tracking number so that it is on record.
I know this may come of sounding condescending but please read the brochure for GSRA so you know what is covered and what is not.
So often these blow ups about GSRA are really because we do not take the time to thoroughly read the brochure/contract.