Leak within twin wall

[This won’t doo]

today we had a leak coming in through on to a log burner fitted by a company in Southampton ,
when we removed the fire to have a look we found the water was coming in via the small locking lugs in side the twin wall and on the video you can plainly see it dripping through , see video

all you log burner installers , out there can you give any explanations for this , we have removed the twin wall from the saddle through the roof and checked all joints but it’s getting in between somewhere , any help would be appreciat

 

[begreen]

The bottom of the flashing looks wrong. It should overlap the shingles at the bottom. It looks like instead is may form a dam. If the gutter to the right is dumping water in this same location then it could create a problem.