Deposited Cheque FNB lost by them

My name is Luisa MDS Nunes, I bank with FNB at Jacaranda branch Pretoria where I always deposit my overseas pension cheque every month from a pension fund in Portugal. At the branch the cheque gets cleared by a staff member Mr Willy and the manageress Mrs Mandy and made paid up immediately. This cheque refers to October 14 pension and was deposit on 23/12/14. Ten days after the deposit Mr willy contacted me to say the cheque was lost by citibank, the intermediary that handle the cheque, and FNB and I had to pay the money back to avoid being blacklisted and my account went negative.They referred me to Mrs Romaine de Klerk and Mrs Sofie at citibank who acts as intermediary for the Pension Fund. At citibank they told me they don't deal with public direct and FNB should handle it themselves on my behalf. Back at FNB was told they could not do any more for me and I must contact the pension fund in Portugal and handle it myself and warn me once more of my account being negative and the blacklist story. to phone Portugal would cost me money, am just a pensioner, I feel the lost cheque shouldn't be my responsibility. Please help. Than k you Luisa MDS Nunes