HOUSE AND HOME REFUSES TO REFUND ME

I bought a DSTV decoder from House and Home at the Pavillion. I was told I must open it to get the number to call to arrange installation. I called the number, I got hold of 3 installers. The Installers agreed to come and install, but on arrival at my place they saw that the decoder was Arial King they all refused to install it saying they do not install Arial Kind decoders because they experience payment problems . Yesterday, I returned the decoder to the shop but they refused to take it saying it is opened. How was I going to call the installers if I did not open it as the contact number is enclosed inside the box? If they refuse to take it back what am I supposed to do with a decoder that no installer wants to install? I had to buy another decoder which they gladly installed as they said they do not experience problems with the company. I paid money for that decode and House & Home refuses to pay me back even though the till slip is there. On the till slip it's written "Keep it for guarantee/ warrantee. Aslo keep it for refunds and exchange"