Roof valley refurbishment and repoint

SilasMarner

The two valleys on our 4 bed. det needs sorting out. They run the full depth of the roof. I wonder if someone, who is knowledgeable in this sort of thing, will give me their view on this quote please. I am especially interested as to whether the "special foam" is usual and effective or a "quick fix". Thanks for your help:-

1, Remove all the old mortar and debris, from both side elevations, of the valley over the front door. 2, Back fill both sides with specialised foam.Re- fill and point both the required edge fillets, using ( water proofed ) mortar with added granite dust as required.3, Clean the affected gutters remove debris from the site. Total price including all labour and materials…£ 475 – 00