The Customer requests the Bank to honor and to debit his account all cheques, drafts, bills, promissory notes, acceptances, negotiable instruments and orders drawn accepted or made out to him, and to carry out any instructions he may give, in connection with his account notwithstanding that any such debiting or carrying out may cause his account to be overdrawn or an overdraft to be increased. Where no overdraft has been agreed or the limit of overdraft agreed has been reached, the Bank may nevertheless refuse to carry out any instructions which would result in there being an overdraft or any overdraft greater than that agreed, as the case may be.