Tickets for Leonardo Da Vinci Exhibition Tuesday January 10th ?

Hi - I have 2 tickets for the Leonardo Da Vinci Exhibition for Tuesday January 10th at 1pm -130pm entry time. Face value of the tickets is 16 pounds each but the cost is 45 pounds per ticket Easiest way to reach me concerning how to arrange is by phone/text on 0796 408 5360. Happy to meet right nearby the National Gallery just prior to your entry in order to facilitate exchange as I will be there anyway. Cheers,