Bad service and harassment from Ackermann's debt collection department

I am an account holder Ackerman's and took an insurance policy but later cancelled it, but then Ackerman's clothing account took over the insurance premium(that is cancelled) and billed it under their account and i do not owe them anything. Now they are busy calling me and telling that i owe then and when i asked them to check when was my last purchase they can see that i haven't purchased and that i do not owe them but i owe the insurance which i have cancelled. I went to the Ackerman's store to query and they called the insurance company in January 2025, but the insurance confirmed that the policy is cancelled and it even lapsed and sent a proof that the policy is cancelled. And now i get harassed by the Ackerman's call center and they said yes it has lapsed in December 2024 but now is active in January 2025 which does not make any sense.

TE Mutlaneng