How do I pay an Avon bill from 6 years ago?

My Mum took Avon out in my name, and for some reason didn't pay the last bill, I went away working on Cruise ships, and when I tried to become a rep a little while ago they told me I couldn't because of the bill, I've now moved house and don't know where I put the letter I had from them to tell me how I can pay, I need to do it online as I'm out of the country again but not sure how I do that or what to ask Avon. I have internet banking so I just need Avon's bank account number and sort code, but I don't know how to get this, anyone got any ideas? Thanks Gem xxx