Why do I get charged when someone makes a mistakes and asks for a refund?

[timberfreak_73]

Someone bought some of my items, but made a mistake and wanted a refund.  No worries, wouldn't you assume that the money goes back and the refund is done....NO...not here, I was out of pocket for someone elses mistake.  It was only 30 cents, but it's not the money.  Why does this happen???

[gutterpunkz05]

As per T&C's ,  30c per transaction, non refundable.

From memory it is actually  33c,    30c + GST