How do you get a refund when you are out of the country

I purchased luggage from AA branch in Benmore. When purchasing the bag I told the attendant that I would be travelling that evening and was not sure if the bag was the right size. The attendant said no problem, I could return it as long as it was not used. The bag was too small so I found another old suitcase to pack in. On my return I went to get my refund. I was told that their policy is to return within 14 days and that they would not honour the refund. I have enjoyed that shop and supported them a lot over the years. I have also often thought of taking out their AA insurance. If they do not honour the small stuff, how will they honour the big stuff. Unless they take action they have lost a customer for life. Smacks of a struggling organisation that once the money is in their bank they cannot afford to look after the customer.