Spain's peaceful "indignant" protest movement, which saw its image tarnished by outbursts of violence in Barcelona this week, has turned its attention to stopping banks from repossessing people's homes.

On Thursday morning a crowd gathered outside the home of 74-year-old Luis Domínguez, in the Madrid dormitory town of Parla, and prevented court officials from serving him with the order to leave his home immediately.

Domínguez, who walks with crutches and is being treated for a heart condition, said he would have been left on the street if protesters had not come to his aid.

"I only heard about them helping people to fight off the banks last night, and this was all organised in a few hours," he said in his apartment, shortly after protesters had seen off the court officials. "It is amazing that I am still here."

An appeal put out on Twitter overnight for a flash protest at his front door gathered enough people to prevent officials entering Domínguez's home.

On Wednesday a crowd of several hundred had also stopped police and court officials repossessing the home of a Lebanese immigrant family in the Madrid neighbourhood of Tetuan.

Plummeting house prices have left some Spanish property owners with negative equity and threaten to push more into the same position as Domínguez – who can no longer pay his mortgage.

"I remortgaged my home for €145,000 and I still have the document showing it was valued at €280,000 three years ago," he said. "Now the bank wants to take the apartment and make me pay them €90,000 on top."

At the height of Spain's decade-long property boom banks were handing out loans of up to 100% on the value of homes. But a crash that hit in 2008 has left more than 700,000 newly built homes unsold. Prices have fallen and banks have become major residential property owners, mostly because of unpaid loans by developers.

The number of house repossessions is swelling as unemployment hits 21% and eurozone interest rates rise. Now campaigners say about 278 homes a day are being repossessed.

"This man was too ill to be left without a home," said Eloi Morte, part of a Madrid-based anti-repossessions campaign born just two weeks ago. "Thanks to the protesters we are able to gather a lot of people in a very short period of time."

"Yesterday court officials and police simply turned around when they saw us in Tetuan," he said. "Today we were able to tell Parla officials that we had presented a writ in the court explaining that Luis was too ill to be thrown out without plans to rehouse him."

The movement to stop repossessions in Madrid has emerged from the Spanish capital's Latin American immigrant community. Immigrant labourers flocked to Spain during the construction boom but are now among those most likely to lose their homes. Campaigners want Spanish law changed so mortgage debts can be cleared simply by giving banks the keys to the property – as they are in the US.

A similar campaign against repossessions has been active in Barcelona for much longer, but the "indignant" movement that emerged after tens of thousands of protesters occupied Madrid's Puerta del Sol square last month has provided a new wave of activists ready to help out across the country.

The Madrid branch of the movement has denounced violence by some of those who blocked access to the Catalan regional parliament in Barcelona on Wednesday as it voted through spending cuts affecting education and health. "We radically condemn any violence and especially what has happened at the Catalan parliament," it said. Objects were thrown at police, deputies were attacked with spray paint and a blind politician said protesters had threatened to take away his guide dog. Protesters claimed police provoked incidents.

"This was an unprecedented event in the 30 years since democracy was restored," Barcelona's La Vanguardia newspaper said in an editorial.