Fed up with blue label connect

I've been having problems with blue label connect since November 2023 when they deliver me a tablet I wasn't happy with i they fetched It within seven days and asked for my contract to be cancelled which they say they but some they never cancelled the debit order which still deducts money even today.ive been calling them every time and they keep telling me about ascalating the matter to the relevant department I don't know what to do anymore I just want my refund