I bought my headphones in March and it worked well. For a month now, it has not worked at all. I am really disappointed. I put a lot of money for these headphones. I tried everything but it no longer works. What can I do ? are there any guarantees?
Best bet is to contact support (link through additional support up the top), enter your serial number and that will tell you what options you have. Most likely if it's a new product purchased from an authorised reseller and you have a proof of purchase, they will fix you up.
Just to clarify, the QC1 haven't been available for a long time probably over 10 years, so putting that serial number into the support page will confirm which headphones you have.