Question about Sennheiser Momentum 3

Good day I bought these in-ears not long ago. Almost from the beginning I had the problem that the right side is less loud than the left. At the beginning, they were still usable due to the hearing aid and the left-right volume distribution. But this problem got worse and worse. It can't be due to my mobile phone software that the problem also exists otherwise. Sometimes the left-right difference is less and sometimes more. It really annoys me and I think it's a shame. Does anyone have any ideas what I could do or what the problem could be? Thanks a lot Greetings