New contract applied when I moved

I took out an 18 month contract in March 2022. When I moved home in Feb 2023 I contacted Virgin to take the contract, which was due to end in Sept 2023, with me. At the time the Virgin person on WhatsApp customer service confirmed my existing contract details and asked me if I wanted to change anything. I replied that nothing should be changed (I have the WhatsApp messages that confirm this). Today, I contacted Virgin to cancel as I’ve been out of contract for 6+ months. I found that Virgin put me onto a new contract (same terms higher price!) at the time I moved and the woman today told me I can’t cancel until August! For a contract to be valid there must be an offer and acceptance. There was never acceptance  on my part - in fact I expressly said nothing in my old contract should be changed. Therefore I need Virgin to cancel my contact, not fob me off and tell me it’s not possible. I have also raised a complaint regarding this matter.