I sent a query by webnote in the middle of the night. By 1100 the next morning, someone had physically checked the product and emailed me a reply. The reply actually answered the question I had asked, which seems surprisingly uncommon in customer service. They'd read my query, as opposed to skimming it for keywords and regurgitating a standard "answer".
As a comparison: getting an answer to a query to npower took me 8 days, 3 people at their end and me sending several screenshots with the relevant sections circled and explanatory text added.
OcUK does customer service correctly for a company that wants repeat business. That's much rarer than it should be, since far too many businesses are only concerned with cutting costs and gouging as much profit per sale as possible with total disregard for their customers, who they see only as marks to be manipulated into buying more stuff whether it's any use to them or not (i.e. upselling). I've even heard OcUK staff advising a customer that it would be in their best interest to not buy something from OcUK at that time but to buy second hand instead. It was the right advice for that customer - they had a dead CPU on an obsolete platform, so buying new would require motherboard, CPU and memory at a far higher cost than a second-hand CPU which would do what they wanted more than adequately. People return to a shop they get good advice from and they tell their friends about it. In the long term, it's far better business practice than upselling at customers.