Perhaps it is me, but I have learned to be a hard nosed negotiator when it comes to money.

Since the shop has quoted you $800 to replace the bearing plus $150 for diagnosis, I would tell them that if they are unable to perform the work as quoted, you will pay them $150 for the diagnosis.

Send a tow truck to the shop and have your car transported back to your place where you can easily deal with the problem ON YOUR TERMS.