Price fixing and vat *****

Yesterday I was looking for loctite block sealer they told me to not buy it but buy Holts wonder weld instead for R138, today I visited vikings Midas they sell Holts for R60. I took it back for my refund at first the asked for the very same card I had used for purchase for transaction to go through, after handing it to them they told me I should give them any credit card my card is a debit, told them I don't use credit card then he offered cash but at 15% vat but I don't have the product as to why his charging vat I don't know so he deducted 15% vat from my refund. This is price fixing, *******, dishonesty and very ********* to influence customers on products they sell 2.5 more expensive than other stores. I took pictures of both prices and products, I want my 15% Vat they going to sell that proctucts again with vat to someone else then charge vat for refund, how much vat is generated from one item?