String Trimmers

I bought this product on May 29 and it has never worked correctly right out of the box with the head that came with it. The cord will not advance.
The directions say 'do not return to retailer'; so I called Customer Service and was told to 'return it to retailer' or I could send it to repair service to be repaired at my expense or take it to a service center locally at my expense. This isn't acceptable to me, I bought it in good faith and used it until the line broke repeatedly in the first 30 minutes using it on grass and dirt, no contact with hard surfaces.
I need something done with this as it doesn't do me any good when it doesn't work.