> I've seen some credit card and bank card forms that include language which make the agreement void if its terms are altered in any way.

How's that supposed to work? Bank offers agreement. You offer totally different agreement although superficially similar. It's not altered. It's new. If bank agrees then I don't see how it could get away. After all they are big supporters of the rule that if you signed something you declared that you agree with it and if you actually don't it's your loss.