Avios estore (not BA) give 4Avios/GBP on Apple UK including iphoneX
Similar 4,000 Avios from carphonewarehouse on 24 month contract & iphone X
‘Reduced rate’ could be anything.
You should consider what you might pay, in Dixons, and get back, from Heathrow Rewards, if you’re passing through T5 soon.