A UK police force is facing fresh questions over its approach to vulnerable individuals after it emerged a disabled mother and son have endured years of abuse and violence, near to where a disabled refugee was murdered in 2013.

Ruth and Zac Jones, from Bristol, say they have had a brick thrown through their window and four vehicles set on fire, among a series of targeted attacks similar to those that preceded the death of Bijan Ebrahimi in 2013.

The Joneses have logged more than 50 complaints with police over four years, but claim they are still targeted on their estate in the north of the city.

Zac, 29, who has a rare skin condition that he says leads to him being bullied, says that neighbours make homemade signs falsely alleging he is a paedophile.

Ebrahimi, 44, had reported death threats and racial abuse to police for seven years. He was murdered by Lee James, a neighbour, who wrongly claimed he was a paedophile. Days earlier, a mob had gathered outside Ebrahimi’s council flat, chanting abuse, but police called to the scene arrested him instead as the mob cheered.

A police officer and a community support officer were convicted of misconduct in a public office over their response. An independent review into Ebrahimi’s death also concluded that Bristol city council and the Avon and Somerset police force were guilty of institutional racism in their dealings with him, the first judgment of its kind against a local authority.

Now Zac and his mother Ruth, 57, who only has the use of one hand after a brain haemorrhage, believe they risk a similar fate. “Police have failed us – we will be the next Ebrahimi,” Ruth told a BBC Inside Out West documentary, to be screened on Monday.

One officer – since dismissed for sharing racist posts on Facebook – who was investigating the targeting of the Joneses believed that Ruth was the aggressor and not the victim, and had even smashed her own car windscreen.

Police say they have been working with Ruth and Zac Jones, including putting them on a “problem solving plan”.

Zac, who believes he and his mother are being targeted because of their disabilities, said: “It’s just awful. We just want to be able to live our lives properly. The police have failed us. They’re no help.”

“I just think the police should do their job; if the police had done their job three years ago, I wouldn’t be in this situation,” added Ruth. “I’ve ended up, and Zac’s ended up, living as victims.”

The chief inspector of Avon and Somerset police, Mark Runacres, said the “force has made great strides since the Ebrahimi case”. He added that having studied the call logs of all of the incidents, the sentiments of the dismissed officer “are not reflected in the response” of others.