Service Sucks

On the 26th of June I purchased I refurbished mixer at this place. Used it over the weekend, wanted to use it again the evening of Tuesday 2nd of July and it wouldnt work. After many attempts to switch it on and off it didn't want to work. I then called this place the next day and the sales person said it could a small fault, they would hve to fetch it and check it and if it was indeed broken they would fix it as they do on site repairs as well and then send it back. I then requested that it not be fixed and would like my money back as it is less than 7 days old, they then advised about terms and conditions i wasn't advised about when I bought it, I never even got an invoice, as their system was down and they would then email it to me. On Thursday morning they then called to check if the mixer had been picked up as they couldn't wait to get hold of it to see what is wrong. Once the mixer left I then had no contact from them until I contacted them myself the next day. They then needed to check if it came in. 30 minutes later I recieved a call saying it's working. Why didn't they contact me immediately once they got the mixer? It was on the premises, where they do on site repairs as well for very long. What do I have to gain from this besides making myself look like a fool yet loosing business in the process as the mixer has been there since Friday and still is. All I want is just my money back so that I can move on so I never have to do business with this company agin.