Unitel Direct Group review: Not sure as I have never been sent any information yet

I have been hounded by a company called Unitel that ho claim I have signed up to a £500 per month subscription, they have subsequently taken £990 from my account without my consent and are now hounding me two or three times a day for more money, I have asked for to ask what I am paying for but yet they have sent nothing. At first when I took the initial call, their service sounded good, I gave them a card number but they told me no money would be taken until I was happy with everything to proceed, but after reviewing them online, I decided there was too much negative feed back so I declined their offer. However they proceeded anyway and withdrew £990, until I noticed to have since stopped the card, but they are now hounding for more money, but I have no idea what I am supposed to be paying for,
Please can you help with this matter

Thank you