If it has been more than about three days the novation sticks. The attorneys probably got that call in within the three days?
They are trying to make you cancel the account. You have agreed to verbally now (if they show you a law). I would not have done that. You can tell them you changed your mind. You like the account and the signature card the way they are. But I would not bother. Just keep on using the account like regular...
Wait a minute; is it an interest-bearing account? They might have to change that to non-interest-bearing. You are not granting the benefit of fractional lending so they should not be compelled to give you the benefit of interest. That might be what they are standing on for a cause to reject the non-endorsement.
Look at your papers and get back to us please.