Not accommodating

I live in cullinan and bought a faulty mass air sensor for my isuzu d-teq. I tested the sensor on their premises and found it to be faulty. Returned it but they did not have another in stock. I was told they can get another for me but I prefered to get a refund. They sales person was very helpfull but had to confirm with the boss. I left my acc. details for a refund but they called and insisted they must take a 20% handling fee and i must come into the shop and swipe my card. I live 65km away and no matter how nice I asked the boss just wont accommodate me with a eft. That is a 130km round trip, I am very disappointed and won’t be shopping there or refer them again.