Service Cancellation

I have cancelled my service with you due to slow internet, i am still waiting for you to come and collect the device because i know if you don't you are going to keep on debiting my account. I also see on my rain profile that there is the next billing date, how so since i cancelled. Sort it out because i don't want my account to be debited end of this month as i know the refund process is going to be cumbersome.