Stores cheating customers.

I bought a phone Samsung A20S dual simcard. And I was issued with the phone in a box that says dual Sim card. I didn't have a second simcard at that time, so I was using it single Sim for at least a week. Then when I received my second simcard I realized I can't fit it. When I went to the store to ask them to help me fit it, they said they will take it to vodacom to check if it will support dual Sim. When it came back we went to the shop and the manager there said she can't replace the phone nor refund us. They say their policy does not allow them. They never explained any policy to me and their slip does have such a policy. They made me feel stupid trying to cover the fault that they did when they were handing over the phone for the first time or rather they were cheating us in selling the single simcard phone for the price dual phone. At this point they never refunded any Change because the prices are different. They ditched me and said there is nothing to do with the phone I must use it or buy another one.

At this point I do not know what to do for I can not pull a gun on them and demand my refund. I really need your assistance to align the store to the customers interest coz my slip says dual Sim but my phone is not.

They even over charged me for the phone I'm using and they don't care. They say there is nothing they can do.

So is there something we can do on this regard or I must just suck and live? ***