Duplicate order

On black Friday I had bought items for the value of + R600 beacause they had a 40%discount and I love their work and customer service.I paid for the item via online then I kept getting messages that my order wasn't paid for n that I need to pay for order so I thought maybe they payment didn't go through so I went n I paid for the order via eft. Only to find out that the order was duplicated and two set of the exact same thing was sent to me. When I phoned and checked They said I had placed the orders However I had only placed one order and their system had given two order numbers. When they checked again it was a few minutes of each other the order. I was told that sometimes if you press the back button it duplicates the order. I was unaware of this. However I paid 2nd time without checking that the order number was different. The funny thing it the day I phned and said I checked my bank account and saw that the was two payments to them the very next day they 2nd set of of the same order was sent to me. It was not even my fault and I had just paid cause I knew I had only one order placed. Everyone looks for a good black Fri special and this one just costed me more. I took order to Johannesburg to speak to the in person which I had told them I will do during they December period. But when I get there I find out that they where closed and that they where opening when I will be back in durban. I called them on many occasions and asked them to take the items back and refund me or even just give me a store credit. They refused their option was tha they will give me discount on a purchase that I make before end of February which doesn't help me it just puts me in more expenses. Very very disappointed with them. Because they have always given me such great service and great quality.