Credit card being charged without permission

Dish was installed on a Saturday .  I called on Monday to cancel the service.  I was asked to sign giving them permission to charge my card for the installment fee.  There was nothing to read but the line to sign for the one time authorization.  I received my credit card statement with a $440 dollar charge from Dish.  I notified them that I did not give them permission to charge my card that the charges need to be reversed.  I was told that I had signed a contract giving them permission to charge my card. I did not give permission for that.  Dish is committing fraud against people .  Dish said they will not reverse the charges.  I asked for a copy of the contract.  I have not received a copy.  I was never notified of the intent to charge my card.