Mortgage declined for moving home

Just advice for others if you get declined a mortgage raise a complaint immediately and it helps.
I'm in the military and live in Service Accommodation, I pay £440 including council tax a month for it. I also own a house which I pay £720 including council tax for a month, so £1160 total.
Natwest declined my mortgage when I wanted to move house and port over to a smaller mortgage of £190 a month and out of the service accommodation which would save us £830 a month after council tax and this was declined. I complained as it was obviously easily affordable, took a few weeks of going back and forth with emails and they realised it was much better financially and gave me a small £250 "we are sorry" compensation and the new mortgage deal.

The main point is...... Even if the computer says no, push them and ask! If it's affordable then they will let you do it!