Total incompetence!

I was hoping for a special present of an 8’x6’ Summerhouse for my wife’s special birthday.
Having notified MPB that there was only a 7’ access to the back garden due to a brick arch over the gate, the fitters turned up with an 8’ back panel. However, it was only after they had erected 3 sides of the building that they decided to tell me that they couldn’t get the back panel through the gate. They must have known it wouldn't go through and they should not have started erecting it.

They then told me that they had tried to lift the panel over the wall but they were afraid they would knock the arch over. Apparently, the fitter’s version of events to the company was that the panel was starting to bend. For a company that claims their ‘buildings are designed and built to the highest standards’, to bend in that situation is highly suspect!
At this point I asked them if I should remove the arch. They led me to believe there was no other option, and so they stood there and watched me get my shoulder under it and heave it down! It came down in big chunks leaving me to believe that the fitters, trying to get the panel over the arch, had dislodged it and made it unsafe.
They then finished the main structure but then told me they hadn’t got any skirting or trims to finish off the inside. I pointed out one of the obvious faults of the double doors hitting each other at the top but having a 10-12mm gap at the bottom. I was told it was because of uneven drying out of the timbers!? And they left. I later measured the width of the front panel at the top and compared it to the bottom and found there was a difference of about 13mm. The left hand side panel had not been pushed up to the base leaving a gap underneath you could get your fingers up.
Other problems included: The internal panelling on the back wall was at an angle; approx. 30mm out of plumb from top to bottom. It was also pinned in the middle of each board which would mean after a short time they would all warp. A trim round the back was only fixed one end; the rest was blowing in the breeze. And there were 5 spare holes in the back barge board where the fitter had problems finding a fixing.
So it was arranged for someone to come and rectify the problems and finish the interior on 7th April. I took another day off work (without pay) to be there. He didn’t arrive till late morning, but when he did arrive, he had been given the wrong information and didn’t have the materials to do the work. He did come back a few days later and it took the 2 men almost as long to rectify the faults as it did for the original fitters to erect the summerhouse. After they left, I found that the hook to hold one of the doors open was now 50mm short. It says, ‘MPB Garden Buildings employ a team of highly trained fitters….’. Really!?
With the problems with the arch and having to take an additional day off work I thought it appropriate to ask for some compensation. I had phoned the company about the arch and was told I would receive compensation, but this has since been rescinded. Compensation for having to take another day off work because of their incompetence has fallen on deaf ears. The only compensation MPB have offered is to re-treat the summerhouse in 12 months and to extend the guarantee to 24months. But as I have just treated it with Cuprinol which is good for 4 years, re-treating it in 12 months is pretty pointless. But perhaps I should take them up on their 24 month guarantee because I have absolutely no faith in its construction.