Bad Service & Poor Quality of Trampoline

A few days before my sons birthday party we bought him a trampoline, which I started to put up the evening before his actual birthday. When I tired to put the piping to hold the net up, it just wouldn't work, no matter what I did. I then on my sons birthday the next day went back where I bought it and asked them about this, they eventually came out to try and fix it, which they couldn't and said they will come back later that day. They came back later that day with new parts and it still wouldn't work. I had to improvises as my sons birthday party was the next day. I spoke to the manager that day and she said this is a know defect/problem/issue on the trampoline and she will check into it and get back to me later on in the up coming week. I'm still waiting on the call, so about a week later I call back and couldn't get hold of the Manager as she was so call busy, so I left a message and they advised me that she will call back later that day. Its now about a week later and still no phone call. The service I'm receiving is appalling and unacceptable and I'm not letting this go...