O2 Online Account Security???

Karen575

Hi everyone, need advice please about reporting security issues with an O2 online account.
At the end of December I had a scary experience. When I logged in to print out my bills to catch up on paperwork, I realised why I had stopped receiving the paper ones by snail-mail a few months previously...a completely different customers details (and security info) appeared against my phone number.
I got straight onto Customer (non)Services, and yelled. They assured me it would be sorted inside a week, and I changed the Username and password a second time after the call ended just for my peace of mind.
Logged in today after receiving an email reminding me my bill was available online, and guess what? Still the other customers details, and bill. NO sign of my info anywhere.
I find this really worrying. Luckily I am not the sort to commit ID theft, but now have all the tools should I ever wish to.
What and who do I threaten them with to get this fixed? Is it an Ofcom matter? Data Protection Act breach? Apparently its not possible to delete an online account with them.
And has anyone else experienced this? Part of me thinks I should also warn the other account holder - what do you all think?

DUTR

Do whatever you think is right, yelling at the CS staff is a no no though, it is not their fault is it?

Karen575

Quite right, its not personal and I did make that very clear. She was trying to be helpful and I appreciated that. Point is tho', it still isnt fixed.