On Air direct debit set up without approval.

Please be careful with On Air, they phoned me a couple of weeks ago asking for my details, when I asked why they said it was in relation to a decoder. As I haven't bought a decider since 2015 I asked again why and they hung up, the next day a direct debit appeared and money left my account. I stopped it via the bank after spending hours trying to get in touch with On Air support. They promised to get back to me when I emailed them threatening the Ombudsman, nothing happened. My wife eventually got through to them today, they claim I owe them to payments dating back to 2015 and became very offensive eventually hanging up. My wife asked them for proof of debt even though it is prescribed after 3 years, the lady didn't understand this became abusive and this is when she hung up. The issue is they have my details and set up a direct debit without my approval, be very careful. I will take it up with the relevant authorities if and when I get the proof of debt.