My parents are travelling to Alicante and they have booked a rental car with reference number: ES39564732710.
They have Maestro payment card but they are not sure whether the card will be working for a deposit of 900 euro...
Or may I borrow them my Mastercard just to be sure that you can take 900 euro deposit from them?
Well they can use it online to make the reservation but only these suppliers accept debit cards for the deposit:-
OK Rent a Car
They cannot borrow your credit card to pick up the car and pay the deposit.
Your supplier OK does accept debit cards as it says so on the confirmation voucher:-
¨ This location accepts payment by Debit Card for Car Rental and Excess deposit ¨.