Cancel a scheduled payment & pay now instead

Hi, my service was suspended for non-payment. I scheduled a payment to come off of my debit card for Saturday, Sept. 12th, but I received my check early & would like to cancel the payment for tomorrow & pay today instead. When I made this payment arrangment I still had service & thought this would keep my service from being disconnected, but nope, I was wrong! I know I should probably just wait because I'm sure even if Comcast will do this for me, they will still probably try to take it out of my account again tomorrow, resulting in a hefty charge from my bank cause the funds won't be in there for a 2nd payment. Any help is appreciated.