I bought a sony experia xa1 ultra from a o2 shop and had it unlocked by o2 so that i could use my old sim card after a few months the phone developed faults and i sent it back to the o2 for repair, they repaired it but they had locked it back to their network i was not told that this would happen so i was not sure what was wrong with my phone when i received it back. After getting multiply codes from o2 to try and unlock my phone it ended up locking the handset and i can no longer use it as a phone i rang they up many times trying to get the correct code to unlock my phone and each time i was told a code would be sent to your email withing 72 hours or 7 days or within the hour and each time they never sent a code. They eventually sent me out a replacement phone but it was the wrong model so i sent it back for the correct model phone. They sent my out a damaged reconditioned phone with a pickle out in the centre of the screen. I rang them us spoke to a manager and they told my that they could not send me out another phone and that they could not send me out an unlatching code for my phone because it had never had a o2 sim in it and told my to fix it my self or speak to sony. all this was over 7-8 weeks of me being patient and waiting the times they said. Its the worst customer service i have ever had and would never be with o2 again and would never recommend they to any one.