If you don't want to cut his bangs, you must not let him win. Mylo whom is also 5 months old, used to act the same, but I never gave up. After a few weeks things were a lot better, he still hates getting his hair brushed but when in come time to putting his hair on a ponytail... he actually stays still ...LOL... I think he knows that after that it will be all over...
Just be patient things will get a lot better.