bad customer service ever experienced

On the 20th of August I bought a Samsung washing machine at game in Polokwane,the following day I tested the machine if it was working I put a detergent in the detergent drawer however the water pressure in my area is low as a result the machine couldn't suck water and the person whom I bought the machine for complained that she won't be able to use the machine,I then went to groblersdal and asked if the machine will be able to be exchanged as I already tested it and I'm unable to go to polokwane they said yes.on the 26th of September I called the store to verify they said it's fine I should come for the exchange,when I got there they said they'll inspect the machine for any damages then they said no they can't exchange the machine as it has detergent we should wipe it first of which we did they let me bake in the sun for about 2 hours when they returned they refused and said they won't accept it because it was used they were so rude about everything.after I hired a bakkie that charged Me R650 for the trip and also I pay R430 a month on account for that machine am I supposed to pay for a product that I cant use is that how you treat your customers?