0161 2481616
This is the direct number of their customer service line that the 08704432389 number points to. Hope that helps a bit?
http://www.saynoto0870.com
-edited just to add:
I've never had a problem with returning faulty hardware to Aria, nor with receiving a replacement. However, I have only done this in person at their returns desk. If you're anywhere near Manchester, I'd highly recommend a visit. Most of them are friendly chaps who are happy to help. There's just something about complaining face-to-face that gets the job done.