This is an astonishing deal, if you are prepared to do the cashback claims. I have used this company before and I've had no problems with payouts.
I found this offer via the website comparemobilephonedeals.com for £3.66 which is less than the sim-only deals I found. In order to get the TopCashback offer as well, I added the deal to my basket and then closed the page and went back to AffordableMobiles.co.uk via TopCashback and then proceeded with my purchase which was already in the basket. The cashback is currently Pending at £40.40.
My phone is due to arrive tomorrow. I will post again if there are any problems with the delivery etc but didn't want to leave it too long to publish this deal.
The phones from these sites are also usually UNLOCKED for any network. Fingers crossed that will be the same this time as it adds value to the resale price etc.