Like alfabus says it’s grey area. THe local pikeys will do it for bog all in comparison as they will tack it to the old wood, not use a scaffold tower, pay no tax/vat and never be seen again.
A proper company will strip back to tiles from the eaves, lay down a eaves guard systems, use quality PVC-u and make sure it’s continuously vented soffit board too.
Cutting corners and capping the old stuff accelerates the rot and it won’t be long before you have to do it again.
Best bet is to get three bona fide installers and compare the quotes, ask them what product the use Celuform/swish are the dearest and compatible to Everest quality and then you have Kestrel/BCE mid ground and other import stuff which is cheap, has low silver ratio in the PVC-u and will discolour.