After dining as a party of 2, I received my bill and gave the server a $25 gift certificate and my debit card for the remaining balance. She brought the receipt back for me to sign and as I was calculating the tip I thought the post-certificate total seemed higher than I anticipated. On the itemized receipt that I was originally given before handing my card over that was now stapled under my card receipt, there was a gratuity handwritten under the total on and then my card was run for that new, higher amount. I wasn't given notification of this before my card was authorized and any gratuity policy is not located on their menu or website or certificate. Is this legal?