Cutting external wall insulation

[m0t]

I have a chimney that's connected to nothing and causes water to leak into the rooms to the side and below and want to get it removed.

A few years back I had EWI fitted and what I hadn't noticed was that the fitters hadn't taken account of the change in roof pitch behind the chimney so the EWI ends up being too high at the roof line if I remove the chimney.

I've had some roofers out to quote and they didn't want to touch the EWI and wanted to take out the chimney and roof up to the back of the EWI. This doesn't sound ideal. What work is involved in cutting the EWI to match the roof line?

I'd assumed the render could be cut with a diamond blade and then the EWI with a saw (they used wood saws originally). I think the verge trim was secured with silicone. It didn't seem like a difficult job but the roofers advised not to touch it.

The company that installed it have long since closed once the public subsidies for it all reduced.

 

[bobasd]

there's definitely no fires or appliances feeding up any flues into that stack?

we really need pics from on the roof showing above and below the chimney stack.
why the EWI has been taken above the verge lines is an unknown but pics might help show why they did what they done.
cutting the trim or the EWI is simple enough but needs thinking through.
has the trim/capping been "glued" to the original wall surface?