In reply to Kipper:
Apple is utterly notorious for the shockingly poor quality of its cables despite its ultra premium prices. Take a look at the Apple Store customer reviews for its £25 lightening cable. It got an average of 1.5 stars out of 5 and comments like "I've been through about 5 or 6 of these cables over 12 months" and "I have had a phone 10 month and already 2 of these cables have not lasted the pace. VERY VERY poor apple"
I bought a £1 cable in poundland 4 years ago and despite almost daily use it works fine.
My advice is take your cable(s) back to Apple for an exchange point them to the Apple Store reviews. If they refuse to swap it out mention trading Standards..... that always works! I've had 4/5 laptop power cables out of them.
Why do they do it? Coz they get away with it.
Post edited at 23:29