My experience was very mixed. First to acknowledge is that the price for my iphone 6s contract package, after application of the special XMAS150 discount, was the best I found. However, completing the online purchase form was painful with several attempts because the system did not like my answers. It was also unclear how to retain my existing mobile number. In the event, it failed and I was issued with a new mobile number when the SIM arrived. The delivery process was excellent with both text and email notifications of the courier's impending arrival. Then things turned bad again. On contacting O2 to rectify the SIM problem as suggested in the acompanying leaflet, I could not understand the heavily accented (foreign?) assistant. It took numerous repeats to become undestood and I think she arranged for my original mobile number to be applied to the new SIM. I also queried a bill which had already arrived by email for £35 not the £31 per month I was expecting. She tried to explain that the extra £4 represented a pro-rata for the days between ordering on 31 Dec 15 and receipt of the phone on 4 Jan 16. It can not be right that a customer pays for something which they have not yet received. Furthermore, I was still paying for my original phone and tariff for those 4 days so in effect being double billed. Setting up the phone was a nightmare and took nearly all day to upload via my pc the configuration and content of my old iphone 4. It took two long calls with Apple suppport, the second being over 1 and 3/4 hours. This was primarily due to my using itunes on a Windows pc but nonetheless, I would not yet have a functioning phone had I not been off work that day to dedicate the time. Lastly, my old phone lost service in the evening of 4 Jan 16 but the new one was still operating on the wrong number as supplied with the new SIM. Thankfully, as I write on Tue 5 Jan 16, my new phone is now working with my original mobile number. It remains to be seen whether the billing will be correct - namely, will my old contract be ceased and will the new one be debiting the right amounts? So, in summary a mixed experience. For their part, Mobiles.co.uk need to improve the front end application form or attach explanatory notes because it was not clear, particularly in respect of keeping my old mobile number.