I think it's fairly similar.  I had an online account with BT Genie that was taken over by O2.  When O2 first took over the BT genie accounts they could not trace mine and eventually located it and then managed to duplicate the account.  It was all very haphazard. I had various problems along the way and in September 2003 my direct debit was not collected. As it was so long ago I cannot be 100% sure of what exactly happened, but according to O2 the phone was still being used from September 2003 and I was being billed online.  This apparently went on until April 2004 at which point I have recently been informed a bar was placed on the account. Due to payment not being received.Then in July 2004 the phone was disconnected and in October 2004 the default placed on my account.As it is so long ago O2 cannot give me a breakdown of the phone bills as there billing system does not allow them to go back that far.  They can only give me a total for each month which they are saying stands at £750.I have no idea if these calls are legitimate or not and in all honest I didn't really keep track of the O2 account as I had a Vodafone account as well. After O2 took over the BT Genie account I was always sceptical as to if they knew what was going on and only really used the phone to text as the original tariff through BT Genie was £10 a month line rental and unlimited free texts.I never received a default notice to my home address and until I applied for credit in the last year had no idea I had the default against me.