Invested Fixed Deposit Interest Rate % communicated not honoured

Really disappointed with my recent dealings with Investec. I'm tasked to find the best fixed deposit rate for my 87 year old father. Last year I fixed the money for 12 months at 9.7%. Investec came to the party and gave us the best interest rate. The staff member who phoned me to reinvest last week quoted me 9.71% interest rate and I was happy to reinvest as it was in line with the previous 12 month fixed deposit. I kept asking is it simi**** to the previous rate - not once did I get notified its actually less. Fixed Deposit Confirmation comes through today and it states 9.3%, so its 0.4% less - I phoned Investec and the same person tells me that 9.71% is the nominal rate. Well the nominal rate means nothing to me or my father as the interest pays out monthly for him to live off. I asked him to go listen to the recording as this was NOT specifice. The recording highlighted the fact that the staff member had not explained to me that it was the nominal rate and offered an apology. I have asked for this matter to be referred higher up as I think its shocking service and now my father gets less money in his pocket to live off monthly. Another fact is that there has been no repo rate cuts and probably none expected in the forseeable future. So why the drop from 9.7% to 9.3%. But the main fact is that I was told the interest rate for a fixed deposit for 12 months will be 9.71% and I would like that honoured.