Getting a mortgage on a flat with (wooden) cladding advice

Ngozi

Hi, has anyone recently been successful at getting a mortgage approved on a flat with cladding?

I had an offer accepted on a flat, Nationwide arranged the valuation survey on the 22nd April and ever since then its just been a constant back and forth between Nationwide and the Leaseholder, they're the estate agent too, Belvoir 

On the 1st May, Nationwide requested an EWS1 Cetificate which was provided to them.

on the 14th May, Nationwide said that the cladding would need to be removed, proof of whos responsible for the removal and can the Leaseholder provide proof of funds.

On the 5th June, Nationwide reply saying the documentation they received wasn't on headed paper so cant be accepted (fair enough) and that there was no proof of funds provided for the removal of cladding and that the recommendation to remove the cladding from the fire engineer is being ignored.

Belvoir (Estate Agent and Leaseholder) are saying as the building is below 11 metres high, has an EWS1 form and passed fire risk assessments there is no need or legal obligation for the cladding to be removed.
They also saying that the surveyor didn't raise the cladding as an issue, so a bit of "he says she says" between Nationwide and Belvoir.

Getting the impression that Nationwide will decline the mortgage and having asked round, apparently Nationwide are really hard to get mortgage approvals on flats and as each bit of correspondence with them takes 10+ working days to hear back, feels like just dragging out the inevitable.

I'm going to reach out to a broker to see if they have any recent experience with such things to see if they can help and possibly set me up with a lender who maybe isnt as stringent as Nationwide but was wondering if anyone here recently had a mortgage approved on a flat with cladding and what lender they used.

Sorry for the long post and thans