David Reboredo, 43, got involved in drugs at 16 when he fell into a bad crowd, and has had the support of his parents right through his long-drawn out rehabilitation process.

During a brief relapse in 2006 and another in 2009, he briefly went back on heroin and was caught giving heroin wraps to another addict in exchange for cash.

But he is now completely cured and has been clean for nearly four years – and helps at his local detox centre in Vigo, Galicia, giving talks and workshops on a voluntary basis to aid others in kicking the habit.

He also works closely with a local charity supporting sufferers of HIV and AIDS.

Although he does not have a job, David's charity work and caring for his elderly parents keeps him occupied.

But he has been sentenced to seven years in jail for his crimes in 2006 and 2009, and has been behind bars at A Lama (Pontevedra) since Wednesday.

David's father Edmundo, 81, a retired high school headmaster and sworn translator and interpreter, and his mother Olga, are distraught.

Edmundo went blind 20 years ago because of cataracts, and says David is his 'sight' and cannot manage without him.

They say he is completely integrated into mainstream society and has been for years, is 'a very good person', has been 'very brave' and worked 'extremely hard' to beat his addiction, with his family's support.

But although a recent case of four Mossos d'Esquadra (Catalunya's answer to the Guardia Civil) accused of torturing protesters, the former consultant for Banco Santander, Alfredo Sáenz, charged with false reporting and six politicians on the PP and CiU facing prison for corruption have all been given formal reprieves and are now free, two requests for David's reprieve have been knocked back.

The charities Médicos del Mundo ('world doctors'), Cáritas, the Érguete Foundation, Alborada and the O Imán HIV and AIDS support group are all actively supporting and have signed off his request for reprieve – to no avail.

Antón Bouza, head of O Imán, says David has been a great help for the charity and gives workshops on drugs.

He says David's two offences – which involved quantities of heroin of 300 and 100 milligrams respectively – were those of exchanging the drug with another addict in exchange for the money he himself had paid for it, during two very brief relapses.

“It is not as if he was a dealer who was doing it to get rich,” Bouza stresses.

“He is now a person who leads an ordinary life and yet his charges say he is a danger to society and public health, which is certainly not the case.”

David's brother Marcos, 39, with whom he is very close, says the accused is 'not coping' behind bars and that seven year in jail is likely to mentally destroy a person who has already been through the mill beating his addiction and has been an upstanding and valuable member of the community for four years.

A petition on change.org has already netted over 57,000 signatures in little over a week, and Edmundo has had T-shirts printed in support of his son.

Edmundo has also written to King Juan Carlos for help, and a protest march took place in Vigo on Monday.

But the government – the only body which is able to grant a reprieve – continues to deny David his freedom.

Photograph: David (centre right) with his family – Edmundo (centre left) mum Olga (left) and brother Marcos (right)