Makro overlocker Empisal 760c

I bought a Empisal overlocker at Makro Vereeniging. First of it had no manual inside. The first time I worked with in the overlocker was not working properly. I sent it back and they said they wil fix it. Went I go it back it work for not even a half day same problem. I sent it back again. They didn't wont to refund my money or give me a new overlocker. Same problem for the 3rd time. I live about ****m from Vereeniging and it was a struggle to get the overlocker to and from Makro. The 3rd time they said that the guaranty expected and that I had to pay to fix it. So I did. I reserved it back. I have work on it only a few times and it have the same problem all over again. What am I to do?