Scan number amongst the top PC retailers like Aria , Overclockers and Amazon. The fact I've spent over £2000 on their site should be proof of their customer satisfaction.
I've changed orders at the last minute through their online queries , be it deleting or adding or changing items and had no problems , they are very accomodating ; just don't be afraid to phone or e-mail them as they will bend over backwards if needs be.
The products arrive well boxed with lots of bubble wrap but as with all deliveries , apologise to the courier and check all products while he is there for transit damage etc , it keeps you right. I would also reccommend buying Scan insurance if you are a novice PC builder ( I learned the hard way,luckily it was just a GPU HDMI socket I wrecked).
With bigger orders they are liable to throw in some freebies (usually end of stock items but hey).
The only downside , but this applies to most retailers is the restocking of out of stock items , usually dependent on the unreliable delivery dates of the manufacturers. This is easily rectified by a phone call ; dont go by the listed restock dates on the website as with a small restock number the ' first come first served ' means you maybe having to wait on the second stock delivery .