Is this building quote fair, should we have to pay the full amount (England)

In November of 2025 we noticed some mold growing on a wall in our house (built in 1999/2000ish)

The room is a garage conversion, which backs on to extension both of which were jobs done under thr previous owner ~10ish years ago. We also noticed some fungal growth and moisture in the downstairs bathroom (part of the extension) which abut's the garage conversion.

We had a company come round and identified the issue as rising damp, noting that the workers who did the extension did not put a damp proof membrane down. They visited in December 2025 and injected a damp proof course in external walls and applied a paste to the bricks of the garage conversion. They noted that it could take a full year for the wall to dry before plastering.

In June 2026 the company offered free loft timber checks to all existing customers, the assessor who visited our house was the same person who diagnosed rising damp, he took a look at the wall in the garage conversion and noted that while it was still very wet, that it could take the full year to dry out and it wasn't too unusual.

In July 2026, we noticed some more fungal growth in the downstairs stairs bathroom and water coming through the join of the floor and skirting board when pressing down on it.

Thinking it may be the rising damp issue again, or related, we asked the same company to come round who identified the fungal growth as not rising damp related, but a mushroom that only grows with stagnant water, they took the lino flooring up and the concrete floor was covered in water. The assessor thought that there was an underground pipe that may have corroded and that they would need to dig up the floor, fix the pipe, put a new damp proof membrane down and refill with cement. We were given a quote of £2,500 for all work and paid a £500 deposit

When the builders dug the floor up there was no pipe but digging thr floor up did reveal that there was a drip coming from the wall (shared wall with the garage conversion that had originally grown mold and had the damp proof course in Dec) the builders then said that the pipe was inside the wall, cut a section of wall out and identified the corroded pipe which was fixed by a plumber from the same company.

The company are back again today laying a new concrete floor, but my wife is unhappy with the quote for the work since it seems that digging the floor up and refilling was unnecessary, with the problem ultimately being the pipe in the wall.

The company advertises itself as a damp specialist and and she is of the opinion that they should have some kit to identify where pipework is without relying on cutting and hoping and that the original quote may have been padded with extra work. She has called the company to dicuss and is awaiting a call back.

By brother recommended I post here for opinions on the quote and if it is ''fair' for us to pay the full quote given that the work was completed, but may not have been necessary in the first place