Standard bank home loan complaint

Standard bank does not care about its customers. I was a surety for my parents when they bought a house. In March 2021 we paid off the bond but when I requested the title deed I was told they miscalculated and we must pay R1000+ of which we did. We then waited for the title deed as I sent them an email asking for it and to close the account. Then 9 months down the line I make a follow up on the title deed and was told that we still owe some R4000+ of which I don't know where it comes from because when we settled the account we asked for a statement of the amount owing. I feel they are robbing us now how many times are they miscalculating. I need urgent assistance as we need the title deed to renovate the house