SLK-Vario roof with lack of lacquer and joints

Hello dear community, a year ago I enjoyed the beautiful SLK – used BJ 01/11, bought directly from MB in Böblingen. Recently I noticed on the roof (only on the driver side) that the joint rubber pulls together and small paint gaps are visible. That shouldn’t happen with a 5 year old car…? During the inspection at a MB workshop I was told that they offer me the complete outer roof exchange and the costs I would have to z u 50 % (approx. 1000 €) I am not pleased about this, because I also have the “young star guarantee” for 1 year, whereby I paid attention to the purchase, because a guarantee with a used one was important to me. Well that! “the best – nothing else”. Great saying, but how does it look in reality. Can anyone give me here tips on what this is and how I can proceed here?! As a woman I feel a little helpless and have no idea how I am doing this. should proceed. Would I be happy about expert support!!!!! Best regards Heike