Company claiming i did not pay for goods

I purchased furniture from Decofurn in Centurion on 13 February 2015. My total purchase amounted to R3788.01, I paid R3600.00 in cash and because I was short I asked the cashier if she could put the balance of R188.01 on my credit card. So she did and the issued me with a tax invoice stamped with the word paid. On Monday Colleen phones me and tells me that I need to pay R3600 for the furniture I bought from them, I told her that I did pay the R3600 in cash, but then she said I did not pay. I asked her to check their cameras and see that I did. She responded by saying they do not have cameras and that the cashier is very honest. On the 17 February 2015 I contacted the regional Manager Cornel Mans and he told me the same thing that Colleen told me on Monday however he said that he will deliver the goods but he will open a case of theft against me once the goods are in my possession. I have no faith in this retail store. I am utterly disappointed. I have never experienced anything like this. I will not ever buy anything from DECOFURN again!!!