Thanks for the replies, both, I appreciate that.
Yes, I'm unhappy with the quality of the work all round and, no, there are no comb fillers (though, granted, I'd never heard of them before).
This small porch area is just one part of the work they did. The other was a single story, pitched roof extension on top of a garage / utility room.
For context, the utility section has a suspended ceiling and was uninsulated. I'd also had a relatively minor leak coming through the failing mortar at the front edge of the roof (garage section), and the old felt needed replacing on top of that. The solution from several quotes was to lift the tiles, insulate, re-felt / baton, replace existing tiles, new lead, etc. etc.
Unfortunately, this larger roof is already leaking into the garage (photos attached - first two are the apex of the roof, third is the lower end). So, the work they've done has actually made things
significantly worse. I can only presume that the section above the suspended ceiling is in a similar state, and it's just not soaked through the insulation yet.
I've had the guy out today asking for an emergency fix, and his long-term solution is to lift the top few rows of tiles and install a second layer of felt. He's adamant that the newly installed lead is sound, and that water is travelling up under the top row of tiles.
Now, to me (a roofing layman), this sounds like nothing more than a temporary solution to prevent additional issues in the next few weeks. I've agreed to the quick fix for now as I don't want the suspended ceiling in the utility section to collapse.
I'm going to be getting some other companies out to assess the state of the work and go from there.
Am I right in thinking the proffered fix of a bit of extra felt is nonsense?
Thanks again