I have dealt with Aria as well, but in my case, I returned a faulty LCD monitor and demanded a refund. This took over 4 weeks, and only after some faxes and recorded delivery letters did things get sorted.
I have heard about Aria pulling stunts like this on other forums, so you have to be insisent.
Send a recorded delivery letter to the MD at Aria House
Belle Vue Avenue
and also fax a copy to 0161 248 1615 beforehand.
Hope this helps