Can't Cancel my Vodacom Data Contract

I am still trying to cancel my Vodacom data contract *** which has expired. My mobile reception in my area is not good enough for your people to hear me. It should have been cancelled at the end of last month and i see a bill for this month of R636 . . please cancel it with immediate effect. Thank you.

PS: Don't try and call me because it doesn't work - you can whatsapp or email me.