Incorrect interest certificate submitted to SARS.

FNB provided me with a interest certificate for R29908.00 but when I submitted my tax return via eFiling SARS changed my interest earn to R41212.00. When I queried this with SARS I received this a letter which stated " Take note that SARS received the following interest data in an electronic format from the financial institutions". I contacted FNB on 30/08/2019 and they admitted that they made a mistake and that I will receive a letter correcting the mistake. After numerous e-mails to and from Erin Young of FNB I am still waiting for that letter. On 17/09/2019 she indicated in her e-mail "I have just received feedback this morning indicating that they are just awaiting for letters to be sent from the relevant department and would be issued to all clients that has impacted". I'm still waiting for the letter.