ABSA Complaint

I have been a client of Absa for 40 odd years. My Husband has passed away and I have been trying to contact our personal banker to discuss certain matters. ABSA are not always answering their phone, after finally getting through to them, I've now left numerous messages for this lady who is now working from home and not answering her phone or returning the request to call me regarding my queries. How does one get these matters sorted out so that we can move on with our lives. I find this extremely frustrating.