Brake repair 96 Ciera V6 miles (250,000

Took my car to get the brakes fixed. They said I needed new brakes drums and all. I didnt drive for a while due to a surgery. I went back in to have something checked ( a clicking sound rear) I take it in and they pull the tires off to look at them. It turns out theres a break fluid leaking all over the drum and brake. The guy says oh theres your problem and looks at it and says they didnt change that and pointed at a sponge or rather vertical shaped thing on the brake. It caused a break leak, then says Who did your brakes? I said you guys did and he didnt say anything more. He said it would cost me 170 dollarrs after I paid him 450 I have been talking to a couple of other guys and they said they are under warranty, hasnt been 90 days, can you tell me what you think happened? :(