I was out riding about two days ago when I started to feel like my rear brakes was binding and the bike was holding back .I pumped on the brake peddle and after a while it stopped but then I no longer had rear brakes. Got back home safely checked the bike out. The Brake pads was not warned out the brake fluid was still at max but no brake. I took the bike to the mechanic and he bled out the old fluid while replacing it with fresh ones He even changed all the seals in the cylinder and bled it again but the brake is still spongy and not holding. any help or advice would be greatly appreciated.