There is no universal answer — the right repair depends on the type, extent and location of the damage, which is why decisions should always follow a CCTV inspection rather than precede it.
Patch repair (sectional reline) suits a pipe that is structurally sound apart from one or two isolated problems — a single cracked segment, one open joint letting roots in. A short liner is installed over just that defect. Least cost, least disruption.
Full-length relining suits older pipes with problems distributed along the run — the classic case is earthenware pipe with roots at multiple joints. Lining the whole run seals every joint at once and effectively renews the pipe. More cost than a patch, still no excavation.
Excavation and replacement is needed when the pipe can no longer serve as a host: fully collapsed sections, pipe crushed by vehicles or construction, or runs laid with insufficient fall (back-graded) — a liner follows the shape of the old pipe, so it cannot fix a pipe that slopes the wrong way.
Questions worth asking whoever quotes the work:
- Can I see the camera footage the recommendation is based on?
- Is the rest of the run in good enough condition that a patch makes sense, or will other sections fail soon after?
- Does the pipe have adequate fall, or is grading part of the problem?
- Will there be a post-repair camera pass to verify the work?
A recommendation that is not backed by footage is a guess. Insist on seeing the evidence.