I was making a return journey from Colchester to London Liverpool Street, both on Advance tickets which were purchased through Traingenius. However when picking up the tickets only the outward ticket printed, and even the collection receipt acknowledges that there was 1 coupon to the value of £6.60 (I paid £13.20 for them both). I spoke to the Greater Anglia staff who told me to speak to the vendor. In the meantime, I had to pay full price for the return part of the trip. When I contacted Traingenius, they told me to speak to Greater Anglia as they claim it must have been a machine fault, though given the information on the collection receipt I am not sure it is. Who then is responsible for refunding my ticket?