Don't ever let a mechanic bully you into using that particular service garage. If you're truly worried about hurting the car, you can have it towed for a second opinion or call up other places for an off-site evaluation. Mechanics might try to even suggest that you're putting your family or other loved ones in danger by not having something fixed immediately. Yo, back off, homie! You don't know my life, so don't try to make decisions for me.