Spoke with Three different people in Orange last Friday 2nd July trying initially to get a status update. Not much joy, coupled with much frustration having to re-re-re explain the symptoms, despite the records of prior calls infront of them. In any case they moved my mobile number/IMIE's HLR (Home Location Register). Check out Wikipedia for explanation. Not sure entirely what this means, although good old Gareth who eventuality called me back said that this has fixed a number of UMA cases.
Trouble is, because its linked to my SIM, I now have no GSM/2G/3G connection (BB reports a "SIM not provisioned:2" Error) when I leave the house nor UMA connectivity ay home. i.e. no mobile phone. I was told by Gareth that it takes up to 48hrs to propagate.
The phone came back to life 24 hrs later (Saturday afternoon 3rd July) and has established a solid connection to UMA ever since. Seems the HLR re-assignment worked for me! Thanks to Orange support!