Cancelled contract debiting money 6 months after closure.

In July 2019 I cancelled 3 of my Vodacom contracts due to us immigrating, the outstanding invoice including early cancellation charges was paid and the cancellation was completed. In December 2019, 6 months after the cancellation I suddenly have R570 effectively ****** from my account from Vodacom. When I call to find out what is happening, I get told my contract is active and therefore I am being charged again, for 6 months it was closed?? The proof is on the system that my account was closed in July but then why suddenly now is it active and taking my money?