Flat roof between two pitched roofs

[leeroy221]

Hi,
I have two pitched roofs with a flat gully in-between. This has been leaking into one of the loft spaces and into the bathroom.
I had a roofer come and look at it, the flat roof was in good condition but the side profiles were not high enough so water was overflowing into the loft area (see photos).
The roofer laid some felt over the flat roof and tried to cover the gaps as best he could but water still got in via the gaps. Is there any way I can build up the side profile or fill the gaps that are there? The roofer wants to replace the whole roof despite it being in good condition.
If I can fill the gaps, I am then going to look at getting a good rubber paint and paint over the felt and the gapped area that's been filled. There is sufficient gaps at the other ends of the roof for ventilation.
Any advice or ideas appreciated.
Thanks.

 

[tell80]

Why not post better focussed pics showing the roofs and the gulley?

 

[leeroy221]

Thanks for the reply and Sorry, those are the only ones I have showing the gaps. I have attached 2 photos of the flat roof which hopefully shows more detail of the area.

 

[datarebal]

possibly looks like its been overlaid.. by the village idiot.. get another felter to look at it