puddling on new sarna flat roof

I Would love it if someone would please take there time to give me some advice. The roofer has just completed our roof after starting it two months ago. On numerous of occasions iv pointed out that water isn't draining properly and that it is staying on the roof. In order to correct this he try ed to make the drain hole lower but I think this has failed and that it is the angle of the roof which is causing the water to sit there. will this type of puddling cause us any future problems if not sorted now. I think he's just took the easy option to fix it and hasn't done it correctly. Any advice on how to correct this issue apart from getting a new roofer!! Many thanks

To be honest it shouldn't be a problem.
That being said if I had built that roof to a single outlet, then I would have created a small "guttered" section at the front against the parapet wall, which would have had it's own falls towards the outlet, or set the roof to fall in all directions towards that outlet.

Thank you for your reply .