You've got to be tough with them, I expect the hard sell nonsense and it is pretty hard but everything else has been faultless:-
1st PC they called me to let me know a part wasn't in stock but they could build immediately with an upgrade at no extra charge so I agreed - this translated into another £60 charge made up of something or other and a £25 queue jump charge

Some disagreement ensued and their 'finance' dept is remarkably hard to get hold of. So I rang their sales dept and told them that if they didn't refund my £60 that day then I would reverse the whole amount I'd paid through Paypal and they could take me to small claims for it....I got my money back same day
this PC they were pushing the extra warranty really hard, at a discount for a returning customer of course, but I flat refused...then they sent me a payment request for the value through paypal anyway and I just cancelled it, but would be easy to be fooled into paying it
I'm sure if anything goes pear shaped, which thankfully neither have, then I'll find them a bunch of cowboys on the customer service front. But I did factor that in when buying and I'm quite capable of switching out internal parts/upgrades myself. Strange considering I'm all at sea on specs but I've happily followed online instructional videos to install hard drives, additional memory, sound cards and wireless cards before. One of the reasons I like a nice big roomy desktop over a laptop.