Under cross-examination, however, the complainant was able to give very few details about what happened from when he hired Mr Castles in 2003 until he laid the complaint against him Mr Castles in 2009.
He cited ongoing cancer treatment for the lapse.
"After four years of operations and 54 continuous bouts of chemo, I've suffered some memory difficulties.''
At the time of the complaint he had also started to "self medicate'' for depression with his wife's anti-depressant pills, before seeing a doctor for his own prescription.
Brian Keene, QC, acting for Mr Castles, said the complainant showed a "fairly vague'' recollection of what happened.
Mr Keene said the complainant was warned what Mr Castles' fees would be, but suggested the anti-depressant medication he was taking at the time could have compromised his memory.
The complainant also admitted he did not read all the accounts and documents given to him by Mr Castles, and did not understand all the terminology.
He couldn't say "with certainty'' that he and his wife knew what they were being charged for, but they never contested any fees.
"We went to Mr Castles expecting this to be resolved. Not to be left destitute.''
The hearing is set to resume next month.
