I've used
https://www.elavon.com/ and are quite good
regarding the cancel page - you have to image why would someone be there so understanding your demographics - offering a reduced price may cheapen your product in fact you may want to strengthen awareness instead as to the value yet offering other solutions could be available. So let's say they have alternative payment solutions - if they are hesitant of purchasing either a page of references/customer ratings with possibly a generous return policy to ease their minds may be helpful