Not using an ISP email a your main email account is usually a good idea anyway!
As far as the problem you are receiving goes. When I moved into my flat a couple of years ago I phoned VM to set up my services. They told me that the address already had an account active and that they would attempt to contact the account holder. I knew the account holder had gone AWOL as the flat I purchased was a repossession. I wasn't able to set up a new account until they attempted to contact the previous owner. I was I'd be contacted when they had sorted it out. I was called back within a couple of weeks and was able to place my order.
I'm not sure how useful all my waffling was, but I thought I would contribute
