Here in NY I'd have the answer: Chargeback.
I understand this is not as straightforward in the UK though.
I recently had trouble when ordering something from the UK - not computer related. I received a confirmation that my registration with the firm's website had happened, then a second mail giving details of the 'shipped" order.
When I tried to follow the link the website denied all knowledge of me. I contacted the firm (a reputable one I'd done business with some years ago I might add) and it was suggested I set up the account again. This, naturally had zero effect since the new account showed no order activity.
However I was aware I was on a script here so had to go through the motions if I were ever to get my item.
Two months have now passed so I wrote again pointing out that I was not trying to be difficult but was between a rock and a hard place. The firm was saying they had shipped the order, yet I had no way of checking that it had gone out and no way of tracking the package (assuming that provision for doing that had even been thought of). Additionally, another firm affiliated with the first had delivered a related item to me two weeks before, and I had placed the order with them almost three weeks after the one I was having trouble with.
I then wound up the email by asking when my representative thought it would be appropriate to contact my credit card company and request a chargeback.
Those were the magic words. A mail was waiting for me this morning informing me that the package had been returned to the firm because the address was malformed (typo in the zip code). Now it is quite possible that I typoed the Zip (unlikely, but possible) so I'm not complaining about that. What I *am* complaining about is that it took me making a veiled threat to get someone to go and have a proper look at the situation. The item must have been sitting there for weeks.
This sort of nonsense is why I avoid doing business with UK-based small firms.
I'm not naming names because the original mistake was possibly mine and a good faith effort has now started to put things right.
But Gordon Bennet, what a needless run around the houses for all concerned.