Have you ever cancelled an extended warranty you purchased for your car/van?

I recently bought an extended warranty from the dealership at the time I was purchasing my 2010 Caravan. I regret the purchase of the extended warranty and I know I have 60 days to cancel. Will the dealership give me a hard time? Do I have to go back to the dealer? Has anybody ever mailed their cancellation? Will anything else change on the bill of sale? (interest rate, bi-weekly payments) Does the refund go to the principal amount and just cut down on my term? I understand a cheque will come in my name and TD Banks name (where I got the financing from). Any advice would be great. Will the dealer just get me to sign a peice of paper cancelling the warranty or will a new bill of sale have to be made? The dealership ended up being a$$holes and I am not looking foward to going in there again.