I work for GTR so I've got the PTAC card which allows you 75% off the underground. The oyster card i linked it to was an 18+ but stopped working so I got another oyster card and called up and got the old card transfered to my new card and registered. I then went to the underground got the discount added. It worked for a few days then the discount kept disappearing. Do you think its because I didn't register properly? As in I didn't make a journey then wait 24 hours then linked it to my account? And also yesterday when I checked my online account the oyster card seem to have disappeared then reappeared after. Quite annoying as the oyster card is a non refundable £7 cost