Support can't trace refund

One of the worst customer support I've ever had to deal with. I was supposed to receive a refund from amazon a few weeks ago and they told me it was processed but nothing reflected in my account. Reached out to my FNB and they said there was nothing so I called amazon and they gave me all the info and told me to get FNB to trace the ARN number. FNB has no cooking clue what an ARN number is even though it's designed to trace transactions. The most useless and unhelpful support ever. Considering changing banks now.