How do you link a personal account to a business account?

[grimupnorth]

 Ive not sold on eBay for years because my account went over some magic number of sales and had to become a business account. I was selling houshold stuff and business stuff on the same account as I have been on sine the start in the UK and no one told me otherwise! Anyway they made me open a personal account as well which Ive only used to buy. Now I want to sell some of my kids toys and other stuff off and although the personall account is fine for this there are huge restructions on it as it is classed as a new user. It says that thes limits can be increased if you link to your business account. Ive looked and I cant see how to do this it just says you can. I need to link before I apply but I cant see how, can someone steer me in the right direction?  Thanks in adavance.