Brake Fluid Leak problems of the 2017 Chevrolet Trax

Purchased a new 2017 Trax. At the 3 year mark or near, I heard a squeal from time to time while driving forward. At no time did the brake squeal when applying the brake. At 9500 miles ( 3years)when the squeak happened , no warning lights or onstar indicated there was a brake issue. Monthly updates as to car maintenance also indicated no issues. Upon taking the car to the dealer for service, I was told that mud and dirt got into the brakes and that the car needed new brakes, pads, caliper slides, rotors. Knowing the low mileage on the vehicle and knowing all cars the norm is usually around 20,000 miles the brakes are ready to be serviced. But not at 9,500 miles. Also had a prior issue where brake fluid leaked out of the vehicle when driving at 2500 mileage. I had to have the brake fluid reservour replaced as it was broken . At 2500 mileage the master cylinder leaked into the brake booster and the master cylinder was replaced. Cant help but wonder if that related to later issue with the brakes replaced at 9500 miles. I was told at the dealer that mud and dirt got into the brakes and that the brakes were 'hot" whatever that means. . Had I known that it was a brake issue by the indicator lights and updates on onstar I would have considered it a serious problem and taken the car as soon as possible but I waited as no warning lights and no indication from driving that the brakes were an issue. For some reason I got a credit for 167. 00 on my bill for what I do not know as it showed as insurance? I paid a total of 483. 00 . I can only assume it was for the brakes as they were faulty to begin with. Thank goodness I didnt have an accident while driving. Thanks for listening.