Pension credit tops up weekly income to a minimum of £201.05 for single people and £306.85 for couples, and it can be more if you are a carer or disabled.
A 68-year-old retired taxi driver told us he felt terrible and very stressed out about the loss of such a huge sum, after making futile calls to HMRC and the DWP.
Savers have slammed their terrible treatment by the Department for Work and Pensions after many futile attempts to trace state pension top-ups - which in one case vanished for 10 months.