Widow’s pension + Deferred SRP

My client was widowed in the 1980s.  She received widow’s pension.  She opted to defer her SRP for five years, when she turned 60 in 2005, in order to receive a lump sum that would pay off her mortgage.  She continued to work and to receive her WP.  In 2010, she was informed that she was not entitled to a lump sum nor increased rate of SRP because she had been receiving the WP.  She was not provided with this information at the time of deferral.  She would not have chosen to defer a SRP of £143 a week in order to take a WP of 153 a month.  Legally, this seems correct but morally wrong.  What can I do to help this client?  She has no record of her converations with the pension service back in 2005.