R600 phone cover - No refund

In june 2018, I purchased an iPhone cover using my edgars account card.

When I got my statement I had been billed twice for the same cover.

The actual cover was 260 but I was billed 600. I only received one cover mind you.

I have queried this with Edcon but to dat I have not been refunded, or the matter adressed in any way.

How do u get billed twice for one item .

This is truely unjustified enrichment.

Can this be resolved as I would like to use your services again but cant cos this is really unprofessional. I mean a 600 rand phone cover.