Bad Customer service

On the 14/11/2020 my dad went to deposit money inside the branch to his supplier, he had R25 000.00 with him but now the slip only reflect R5000.00. My dad went to the branch in Greenstone Mall just to find out what could have happened, they lady by the Name of Lolo went to check the footage but came back and there they cant see anything. so I phoned on behalf of my Dad to find out a way forward, Lolo promise to phone me on Saturday but she never did, now i just phoned her she is so rude, she sis not even apologies that she did not keep her promise, she said she cant talk now she is still busy with her reports that needs to be handed in by 11H00, how our business worst part she is a team leader and the branch manager he is always not in the branch, how do you escalate this matter if there in no one to report too. all we need to know is what happened to the R20 000.00 that went missing.