It is Flashband and if you are lucky you may get 5 years out of it but that is a bad job even for Flashband and not snug to the surface, way too deep and it's just wrong full stop. There is a lead apron underneath it and most likely the soakers are in but It should be done in Lead. Seems unlikely that your "roofer" will be willing to change it so may just have to take a hit on this one and leave him a review that reflects his abilities on his website / Facebook etc...