Using MileagePlus Account with TAP Flight
I'm planning to fly TAP this summer, US -> Europe. When I was booking through the TAP website, it would not accept my MileagePlus account number. It stated "The Frequent Flyer Number is not valid. Insert a 9 digits number."
My MileagePlus account number has two letters, followed by six numbers (XX####). Has anyone had success entering their MileagePlus number for a TAP flight? If so, how did you format it?