Brake from the Vitara

Hello, I have a Suzuki Vitara and I'm experiencing a problem with the brakes. They were stuck. I replaced the brake calipers because the pistons were seized. After that, I had to replace the master cylinder because it wasn't releasing the pressure. Everything worked fine after that, until now (2 months). Now the problem is starting again. Can anyone give me a tip on what else I can do? I'm really at a loss. It can't be that everything is defective again after such a short time.