I found Ebuyer to be good though recently the service has been poor. You are not being unfair and you are totally right to be angry.
I would suggest you go for the major firms:
Here is my list of online shops.
1) Dabs.com - Doubt you can go wrong there, though higher prices.
2) Crucial.com - Never get your RAM from anywhere else.
3) Scan.co.uk - Best Today offer deals and good service though can be a touch expensive.
Others: Simply.co.uk, Ebuyer.com
Otheriwise buy from a local computer shop, that way easy returns and warranty situations though expect highe prices.