No decoder Refund at Pep

I bought an open view decoder on Saturday in Secunda mall Pep store, when I arrived home I tried to connect it, it showed me no channels. I then put everything back in the box...I don't know if I read well the slip (receipt) it says you can return everything in the package within 7 days and get your refund but when I went there today the 11th of December, the till operator called the person they report to ( I know her name but will keep it) and the lady told me that she won't do the refund I must take it and contact the call centre to come and help me connect, cause they are selling not connecting though I didn't ask for that I was there to take back. My question is why is it written that way on the slip as they do not do refunds? 2. Is it wrong to take back something that you don't want or its because it was open? Please help