Who Are St1000

Recently i was contacted by phone, by ST1000 communications. They explained the were in conjuction with O2 my network supplier. They said that as my current contract was nearing an end that i was elagiable for an up grade.
After being explained the deal they had to offer how could i refuse, they told me there would be a one off payment for £1.99 for admin fees. So i gave them my card details. (stupid move i here you all say)
They then told me that one of there colleuges would ring me back within the hour to confirnm the order after a credit check. It sounded above board.
After the phone call had ended, curiosity set in. I then rang O2 to confirm details with them and they replyed " we have never heard of this company nor do we deal with them, it sounds like you have been cond"
So then i phone my bank, to be told that payments of £1.99 £1.99 £1.00 £1.99 £1.00 had been taken from my account. At this point i woke up to what was going on, and adviced my bank to cancel any further payments and top cancel my cards and send new ones out.
Since then ST1000 have tried to take out further payment of £1.00 £1.00.
The bank is now treating it as fraud.
I have spoken to ST1000, cancelling the order. And asking why they have taken more than the agreed amount, they tell me they will investigate it and phone me back, also pay all money back. Still waiting. So why do they carry on trying to take more money out of my account.

thanks holemaker! hopefully everyone will learn something from this! companies may offer you great offers but if you cannot put the phone down and get them to ring you back in a few hours to give you time to investigate then it probably is dodgy!