being billed with no product received after cancel

I was phoned with an offer of two tablets with a 24 mnth contract , i never received anything and after phoning I was told the tablets were ****** <br> i immediately cancelled the deal with immediate effect and was told that it was done<br> After a month they started billing me and deducted money from my account<br> this is ******* / *****<br> the matter is not resolved