This Wickes bulb was fine at first and now sometimes comes on at a very dim level (almost impossible to tell it's on) and sometimes at full brightness. I have checked the fitting and all is well there, so the bulb is faulty.Of the few hundreds of LEDs I've installed (none of which came from Wickes), the few that have failed prematurely, have done so on first switch on or in the first few hours of life. Once past that point, most live to, or exceed, their rated life.
Don't worry about the receipt - take it back anyway. Good customer service reviews are essential to this kid of retail shed.
BTW, good customer service appears to be far from the top of Wickes's priorities as they ignored my query and just sent me a 'how did we do?' satisfaction survey instead! B&Q's customer service people similarly failed to address my query and twice simply directed me to my local store, which was completely pointless! These "sheds", as you rightly call them, are just that - widespread and convenient, and very unconcerned about individual reviews (which are always subject to doubt anyway) - there is a constant stream of customers out there who just go there because their outlets are everywhere. It's a common feature of UK retailing these days, sadly.