Do all of the outside pipes which was in a need replacing?

“Any pipework that has visible scorch marks or has been exposed to high heat should be inspected by a qualified professional. In most cases, plastic soil pipes affected by fire or heat damage – including discoloration or deformation – should be replaced, as their structural integrity and performance may be compromised. Shared systems also pose a risk of cross-contamination or failure, so full replacement of affected sections is generally recommended.”

If it's a private house your neighbour must have insurance I'm sure it would cover costs to have soil pipe and the branches renewed

They should be OK unless they are leaking!