People I know have pronounced it as kecks.
Your not the only one...
"Want to go to the CeX shop?"... a line never to be said aloud in public
I'll only buy CDs and DVDS from the shop.
NEVER buy anything from their website, I've bought DVDS from there before and they have been scratched beyond belief and have grotty looking boxes if you saw them in a shop you would put them down and walk away.