Euroline brake drums

Hall people, My Transit year 2004 has had the problem since the beginning that the brake drums rub at the rear with stronger brakes. I was therefore already in the workshop, where I had been told that the rubbing would come from the brake distribution system and showed me a scrap of Ford. But when the rubbing did not get better, I went to the workshop again and they did something, what I don’t know. Allegedly the drums were changed, which I don’t believe. The workshop told me that it was on the tires, or if you change the tires, it was supposed to affect the drums. Has any of you had similar experiences. I am at the end with my patience towards the workshop and will insist on eliminating the defect immediately, no matter with what effort. Greeting Olli