What to do if the contractor walks off the job
If the works have been stopped for days with no explanation, do four things in this order: stop paying, document the exact state of the home, send a written demand with a deadline to resume and, if there is no reply, commission an independent valuation of the work done before another firm comes in. That protects your position on any later route, amicable or legal.
Not every stoppage is abandonment. Waiting for an imported material or a municipal procedure can be reasonable if you are told about it. The difference is the explanation: a contractor who disappears without answering is not waiting for anything.
The first 48 hours: safety and photos
First of all, make sure the home is safe: exposed live cables, open pipes, stopcocks, openings without railings. If it is a house with the roof open, protect it from rain. You can have a professional carry out these urgent measures even while the contract is still in force, keeping the invoice.
Then photograph and film every room with the date: opened walls, half-finished services, materials on site, the contractor's tools. Make a list of what has been paid, with transfers and invoices, and another of what has actually been done according to the quote. If materials were paid for and never arrived, list them separately.
The written demand
The next step is a formal demand with proof of delivery, usually a burofax with acknowledgement of receipt and certified content, sent to the company's address as stated in the contract. It describes the situation, sets out what was paid and what was done, and gives a specific deadline to resume work or explain the stoppage, warning that otherwise the contract will be terminated and damages claimed.
In the meantime, do not pay anything further or sign new documents the contractor puts in front of you. It is worth having a lawyer review the burofax text, especially if a lot of money was paid in advance, because how any later claim is framed depends on that document.
Getting the work valued before touching anything
If the deadline passes with no reply, commission an independent building surveyor or expert to report on the state of the works: what has been done, whether it is done properly and what it is worth according to the signed quote. That report turns your photos into a defensible figure and is the main evidence if you need to recover overpayments.
The report must be done before another company starts work. Once a pipe run is covered or a badly built partition is demolished, there is no way to prove how it was. If time is tight, for example because of a moving date, ask the expert to prioritise the parts that will be covered first.
Routes to make a claim
With your documents in hand there are several routes. As a consumer you can file a complaint with your town's consumer information office (OMIC) or with the Agència Catalana del Consum, which can mediate with the company. If the firm is signed up to consumer arbitration, that route settles things without going to court. If there is no agreement, a lawyer will tell you which court procedure applies depending on the amount.
Which route suits you depends on how much money is at stake and whether the company is still trading. If you suspect there was never any intention to do the work, the case is different; we cover that in the article on what to do if you think you have been scammed.
Finishing the job with another company
Taking over someone else's job is harder than starting a new one. The incoming firm has to check everything hidden before building on top of it: untested wiring, waterproofing with no flood test or pipework with no pressure test can mean redoing parts that looked finished. That is why the per-item price on a taken-over job is usually higher than on a clean one, and it is better to know that from the start.
When we are called in to finish a job, we start with the expert's report and a visit with tests on the services, and in the quote we separate what is reused, what is checked and what is redone. Ask the architect too whether the change of builder needs to be notified in the municipal file.
How to avoid getting here
The best protection is signed before work starts: a contract with an itemised quote attached, stage payments tied to verified work and a proportionate advance. If each payment matches work already done, an abandoned job leaves little money at risk. We invoice by stages under the contract, with a single reachable site manager, and reply within an hour.