P800 reseting the device lock code. Help!

I recently purchased a 4 month old SE P800 of ebay - it was advertised as unlocked but unfortunatly this didn't mean everything. There seemed to be a sim change lock code in place. When i put my sim into it it presented me with the device locked screen. That was friday. Since then me and the previous owner have been sending many emails out to SE customer care etc. He has been trying to contact the owner before him (there have been now 3 owners of the phone) about what the code is as it seems the 1st owner installed the sim and lock code. There has been no reply from him as off yet. What i would like to know is wether the carphone warehouse express repair centre (birmingham new street) has the ability to reset the code back to the default 0000, they say on their website that they can do it on site, but havn't replied to any of my emails about wether they are able to do it to a P800. Does anybody have any experience with this or any knowledge as it would be greatly appreciated. Ive tried all the usual solutions, like try 0000, access the service menu page and reformat (by the way the service menu tells me all locks are unlocked,5) as ive looked around on many forums. Or does anyone know of a solution i have not thought of or discovered. Any info would be useful as ive really ran out of ideas :confused: and im very eager to start using it as all it is right now is a nice, pretty, glowing and vibrating paperweight!