Hi!
I have the same problem as you and the Sennheiser website is completely useless!! I've been looking for an official Sennheiser replacement cable for ages, it seems like it's always out of stock or made by dodgy third party companies. However, I found this website today
http
/www.sennheiserspares.com/index_files/Cables.htm and I've just emailed to ask whether they have it in stock and whether it is a genuine Sennheiser....
If since your post you found a good place to buy a replacement cable, I would be grateful if you could share