Virgin billing me for months for landline they don’t control

I have been trying to get Virgin to stop billing me for a landline that my new suppliers transferred over from them on 4th December 2023. They kept telling me the transfer was cancelled and never happened,but I was sure it had happened as the landline was again working.  It had stopped for a few days after my new supplier came on line.  I have phoned and waited for hours. Transferred from pillar to post with nobody knowing how to solve or check if they actually still had the landline in their control. Told them it was plugged into an Openreach socket not Virgin. Told them I couldn’t use the short code to dial Virgin. They just kept telling me it was definitely in their control and to get my new suppliers to transfer it. I had received confirmation emails from my new suppliers in December to say it had been transferred. The last phone call I told Virgin I was fed up with the total lack of help and support over this. All they ever told me was that they still had the line and would continue to bill me. The second to last person I spoke to that day was getting cross as I was and eventually said in a gloating voice that she would arrange for the line to be disconnected and I would then see my phone didn’t work. Well I believe the phone has been disconnected as they promised a 24 hour disconnection days ago and guess what the phone still works.  As I have said all along the phone was transferred in December. Why couldn’t they check this without them saying it needed disconnection which they didn’t want to do. As they say, HELL will freeze over . . . !