Can a Bank of Montreal cardholder who has exceeded the credit limit on a line of credit (i.e. a co-debt) be held liable for overspending?

Bank of Montreal v. Ralph, [1997] A.J. No. 146 (M) also holds that cardholders cannot evade responsibility on the ground that they exceeded the credit limit. Each time that a cardholder uses his card he gets an advance on a line of credit. If he uses the card he cannot later complain that the lender should not have given the advance. Someone who holds a second card on the same account is not a surety in any sense. He is a co-debtor and is liable jointly and severally with the other cardholder.