Around the middle of July (2009) I received a 'Warranty Renewal Invitation' letter from a company called Digital Satellite Warranty cover Ltd, saying that I was approaching the end of my Sky Digital Warranty package provided by their company. I have no recollection of ever having heard of, much less dealt with, these people before. I am sure I never took any such warranty as I tend not to bother with such things for SKY. If I did it would have been with SKY themselves.
I have not had SKY since April 9th 2009 as I am unemployed and can no longer afford the luxury.
Their letter states that they would like 'me' to remain a customer and therefore hope the package they offer will encourage me to do so. They then quote the table of prices. Below that they suggest that if I no longer subscribe to Sky or do not wish to extend I should contact them by 27/07/09 (this date is in small print) and provides only 10 days for this contact to take place.
I have never in my life received any such notification of renewal from any kind of insurance company where they ask for a phone call to cancel - the norm is to request contact if one wishes to renew. They then provided an application form on the back for renewal with choices of payment methods.
Being under the stress of trying to find further employment I was sidetracked by other issues and did not respond .. mostly because I figured they would need payment in order to renew. It is also very expensive to call 0871 numbers during business hours.

Much to my horror, I have just received my bank statement (2 days ago) and found that they have deducted an amount of £54.99 from my account (via my debit card) which I most certainly did not provide them with or authorise.
I can only think that they somehow got the debit card details from a payment I made to Sky.

Having looked up the company on the internet I find only bad stories about them with many accusations of them being fraudulent.

What are my rights where this is concerned ... are they entitled to deduct money from my debit card in this way without my authority?

I'd be grateful for advice.
Many thanks,
Talia