I was working in a remote part of the Gambia and had the phone unlocked for a local SIM. When I returned to the UK my original Vodafone SIM worked fine for about a week. After an automatic update I got the "Not registered on network" message. Looking into it I noticed that the IMEI had changed. This seems to be a common practise in Africa. Vodafone help was no help at all in restoring the original IMEI and suggested a new motherboard. Is there a way to get the proper IMEI back on the phone?