Can I use a discount/promotional voucher to purchase a Merlin's Magical London Pass or Combination Ticket? No, a promotional voucher cannot be used in conjunction with another such as Combination Tickets. Promotional vouchers can only be used against the offer that is stated on the voucher. Buy Tickets Related articles Free carer ticket bookings Do I get priority entry with a Combination Ticket? How does a Combination Ticket work? What if I'm running late for my time slot? How long do I have to use my Combination Tickets?