Lack of paint after accident, multiple unsuccessful repairs

Hello experts, My Golf had an accident in 2009 (!) (passenger side. Door, B-pillar) – contact with a pendled trailer – and was repaired in well-known specialist workshop (m. E. “Platzhirsch des VW-Gesellschafts” in the greater Nuremberg area). Painting costs over 2,300 €! In 2013 we noticed that on the painted roof in height of the B-pillar the paint had discolored and had partly broken open (the vehicle is used almost exclusively by a driver who naturally höc This first complaint was accepted by the above-mentioned company and fixed for me free of charge. After a further 2 years, i.e. 2015, the same game again. Incident caused surprise to the company’s manager. Nevertheless, the damage was remedied and I was informed that the repair was now more extensive, but lastingly carried out. Hardly 3 years were over, the paint is now flipping off flat, just like lls on the roof of the passenger side only towards the A-pillar. Obviously, the previous repair attempt has led to the laugh now going off at a neighbouring place. The “namous” company now rejects any further discussion or even a repair after a short, rather displeasure-marked examination (conversation in toto max. 5 min.). My questions to the experts: Are the paint removals explainable? Is the behaviour of the company (up to the GF) explainable? n / should I do (technically / legally – turn on RA, or make fist in the bag)? Thanks in advance. HGB