The Royal National Institute of Blind People (RNIB) is threatening the Department of Work and Pensions with court action for suspending the benefits of a blind man after he missed appointments which he was only informed about through letters he was not able to read.

The RNIB has prepared five legal cases against the DWP and said it was looking into a further 50, which relate to the department's failure to send out benefits letters in braille or large print format . In a number of cases, the DWP suspended recipient's benefits leaving them in desperate circumstances, the RNIB said.

The charity's intervention emerged as the DWP published figures showing the total number of sanctions against benefit claimants in the year to September 2013 was 897,690, the highest figure for any 12-month period since jobseeker's allowance (JSA) was introduced in 1996.

The figures published by the Department for Work and Pensions cover employment support allowance (ESA) and JSA.

The figures published yesterday also showed that independent tribunals were upholding nine out of 10 appeals against the DWP. Before the coalition, the number of successful tribunal appeals in any 12-month period was well under 2,000. It has risen to more than 14,000.

The RNIB said one claimant – a blind man in his 30s who only wanted to be named as Robert – was forced to take out payday loans to feed himself after DWP advisors stopped his ESA and housing benefit on numerous occasions over a two-year period.

After having worked most of his adult life, the man from Essex began receiving ESA in October 2011 and asked the DWP to send him communications in braille. But discrimination lawyer Samantha Fothergill who is representing Robert in the county court for full financial damages and injury over his benefit suspension, said he was only ever sent regular print letters which demanded further information and his attendance at appointments.

The deadlines for the DWP's demands lapsed before Robert could get outside help to read the correspondence and his benefit payments were stopped.

"His benefits got suspended but the letters also telling him they were suspended weren't accessible to him. So he didn't know. The first he heard about it was when his direct debits from his bank account stopped getting paid."

Racking up bank charges, and extra payments, Robert was eventually forced to take out a payday loan at a steep interest rate to pay for food. Fothergill said he eventually received backdated payments plus a consolatory payment of £50 but remains "very angry".

"We get these complaints all the time," said. She added that the DWP's system for sending out accessible information was "appalling" and "not fit for purpose". The DWP were "making blanket decisions" to sanction people rather than looking at their individual circumstances.

The DWP said it could not comment on individual cases but that forms were available in braille or large print and that advisers were "on hand to help".

"Anyone who has their benefits suspended should contact us and can, if necessary, appeal," the spokesperson added.

The RNIB's threat of legal action comes as Archbishop Nichols, the most senior Catholic in England and Wales, said the Coalition's benefits system was becoming increasingly "punitive" and was leaving people destitute.

Responding in the Telegraph on Wednesday, David Cameron rebuffed the criticisms saying that benefit reforms introduced by Work and Pensions Secretary Iain Duncan Smith, were part of a "moral mission".

The total number of JSA sanctions in the year to 30 September 2013 was 874,850, the highest since the payment was introduced in 1996. It compares with 500,000 in the year to 30 April 2010, the last month of the previous Labour government.

In the year to 30 September 2013, there were also 22,840 sanctions imposed on claimants of ESA – the chief benefit for the sick and disabled – in the work-related activity group. This is the highest for any 12-month period since sanctions were introduced for claimants in October 2008.

The figures were taken from the latest quarterly set of sanctions totals published by the DWP. Ministers have conceded the issue needs addressing by setting up an independent inquiry into how benefit sanctions are communicated to claimants. Critics claim the DWP is operating a culture of fear with jobcentre staff given implicit targets to sanction claimants.

The large numbers come before the government introduces tougher rules that will require claimants to do more to prove they are actively seeking work.

The success rate of those sanctioned claimants who take their cases to an independent tribunal ran at 20% or less under the previous Labour government. Under the coalition, it has risen dramatically to 87% in the 3 months to 30 September 2013.

Duncan Smith said: "This government has always been clear that, in return for claiming unemployment benefits, jobseekers have a responsibility to do everything they can to get back into work. Research by the Disability Benefits Consortium, the RNIB said, showed an increasing number of disabled people are becoming reliant on food banks as a result of sanctioning policies.

Steve Winyard, RNIB's head of campaigns and policy, said that thousands of disabled people were losing payments as a result of sanctions, and that included many blind and partially sighted people.

"Too often DWP and its agencies are not providing people with the information on what they need to do to receive benefits in accessible formats, like braille or large print. RNIB has won cases against DWP for these very failures. But sanctions have led to blind and partially sighted people being forced to rely on food banks whilst they wait for the government to correct its own mistakes," Winyard said.

• This story was amended on 20/2/2014 to correct a potential confusion in attribution of quotes