Things like this can happen even with the top notch equipment, just not as frequently. I know your frustration. I ordered a hydraulic ironworker and specified that it was to be wired for single phase 220/230. My paperwork even showed that it was ordered to be built this way. When that long anticipated day of arrival came, I discovered it was a 3 phase unit. The dealer apologized and tried talking me into accepting the 3 phase unit with a discount. Since I don't have 3 phase, it would not of mattered if he offered to give it to me for free.
I have a Hypertherm Powermax 1000 and I have never had any issues with it. At work we have a Miller 250 which I believe is built with some sort of partnership between Miller and Hypertherm. We have had many problems with the 250, but most of the trouble came from the Neanderthals not using it properly. I can't believe the dealer you purchased it from would not replace it with a new unit rather than make you wait and loose time and money. I would be contacting Hypertherm direct and letting them know what was going on. They normally have excellent customer service, and follow up to make sure you are satisfied. Something tells me when you get it returned, or get a replacement, you are going to be very satisfied with the performance..........good luck.