Do they have a fixed markup ?, last time i checked Bank alfalah had fixed rates i.e. what ever the rates and installment is at the time of financing, it will remain same for the rest of the years. Other banks just send a notice to u informing that the installment amount has increased.
Though there is one thing, if u r salaried then yr salary should be three times yr monthly installment amount, this is bank alfalah rule.