How's this price sound to you for the auto work I'm getting?

So I am getting my water hose flushed and a chemical thru it to clean mold and mildew found from a blockage of leaves in it. I am getting my back brakes replaced. And my belt does not fit so they are going to tinker with that for me to stop it from squelling all the time. The first price was 852 dollars. I told I cant do that I only have 600 dollars of savings. I was going to just pay for the look and leave but he told me hold on and he could give me something called a fleet discount. This fleet discount dropped it 676. My boyfriend is arguing with me because he wants me to take it somewhere else .. he seems to thinks its a ripoff but id rather just let them do it they have excellent ratings with AAA and BBB. I admit I didnt think service charge would be that much for something i thought seems simple but hey I want it done. It's my boyfriends car but he's letting me use it and I'm paying for this. I don't understand why he is so frustrated. Is this really a rip? Am I being dumb or is he overreacting?

I need a few yes or no's so I can stop feeling bad and he can stop being mad at me.