HTC :: Cannot Unlock My HTC Desire After 2.2 Upgrade

First of all, I would just like to say that I am new to this forum and I apologize in anticipation if I am posting this information under the wrong category. I have done my best to read the rules before posting. Anyway here goes. I am quite desperate because I cannot use my phone as I should. I bought an HTC Desire 3 months ago from Vodafone(in Romania) without a plan so I purchased the phone at its full price. Consequently, Vodafone issued a free unlock code for my phone so I could go ahead and use it with whichever provider I want. For various reasons, I have not unlocked the phone in due time(as I had been using their pre-paid for a while) and upgraded the OS to 2.2 when the upgrade was launched. To be honest, the update came out of the blue and I guess I wasn't realizing what I was doing at the time so I went ahead with the upgrade. Now, after going to the store where I bought the phone they have tried additional unlock codes and none of their unlock codes work! I have tried to get an unlock code online from a pretty respectable unlock provider and still I get: "Incorrect Code" when trying to do a network unlock. I am now in another country (UK) and cannot unlock my phone so I can use it with any of the providers here. It just seems like any of the codes generated of of my IMEI are not working. I don't know much about phones, but this is driving me crazy, and I would really really appreciate any feedback or suggestion here from someone more experienced.