any exchange rate or interest rate quoted by the Bank in response to an instruction is for reference only and shall not be binding on the Bank unless confirmed by the Bank for the purpose of a transaction. Such confirmed exchange rate or interest rate, if accepted by the Authorized Callback Service User through the Call-back Service, shall be absolutely binding on the Authorized Call-back Service User and the Debit Accountholder notwithstanding that a different exchange rate or interest rate might have been quoted by the Bank at the relevant time through other means of communication;