Single biggest mistake of our build

When we built our home, and decided that we wanted PVC double glazed windows and doors. We got quotes from various companies, including Moonstar. We were reluctant to use Moonstar as they are not based in Cape Town. Our builder however strongly recommended them as they were significantly cheaper than the other contractors. What a mistake this was. From the moment deposits were paid we encountered problems with them. As were were building a energy efficient house, we had specified low e glass. When the glass arrived on site our builder noticed that the glass was not low e stamped. With some investigations we discovered that Moonstar had missed this on the specifications. After a lot of back and forth arguments, with Moonstar threatening to walk off site, we ended up paying half of the additional cost difference for the low e. This was not the end of the challenges with Moonstar, many of the windows were installed the wrong way around with the beading on the outside - very easy for burglars to simply remove beading and glass. Many of the windows and doors were badly installed. Every time we got them back to try and rectify the windows, we would find another window or door cracked. In the beginning they replaced the glass after some grumbles, but quite soon they started to try and blame us for the cracked windows. Once we moved in, we noticed that many of the windows and doors were not only leaking air but also water. This they failed to rectify after many visits. Our house is situated very close to the ocean and soon after moving in all the locks were rusty and unusable. After contacting Moonstar they came and replaced the locks with marine grade locks. Thankfully these locks are still working. Eventually after getting them back a number of occasion and after many arguments, we had to get a new contractor in. Thankfully we were able to find a contractor who was willing to assist us. After spending some time assessing our windows he discovered that the incorrect latches had been used. In his opinion it would be impossible with these latches to get an airtight window. He then replaced all the latches for the north facing windows. He also serviced all the windows and doors and got them to a more workable state (some of them had stopped closing over a handful of times – less than 6 months after installation). He also discover that one of the doors had second-hand mechanisms installed. Our large sliding door, which still leaks air and water, he wasn't able to fix. It had been installed skew and the door was incorrectly sized which bends the frame, allowing a lot of air and wind in. It was so bad that you might as well have got normal non double glazing windows, and it would be just the same. In summary, selecting Moonstar was the single biggest mistake we made on our build. We ended up spending far more than the other more expensive quotes and have a far inferior product. I would highly recommend looking at alternative suppliers.