Membership cancellation bully

I had a membership that ended in November 2020 and I enquired about the cancellation and I was told I can cancel whenever I want as I will then be on 'as-an-when' contract since my contract had already ended. I continued until the following year 2021 where I requested for a contract termination which was somewhere around March/April 2021, I was then offered 2 months 50% discount for April-May 2021, I then stayed on for these months and gave notice to end my membership come June 2021. Yesterday 26th November 2024 I received an SMS from an external collection company stating that my account was handed over for non-payment by Virgin Active, I never received any sort of communication from Vigin Active that owe them monies, and also I did give more than enough notice to terminate my membership leading to being offered 2 months 50% discount to stay as a member.