MTN Musgrave(ground floor) disgusting service to an elderly

My mother a loyal mtn customer went to Musgrave branch on the ground floor to enquire about a problem relating to her phone. Sylvester an employee of mtn shouted at her and dehumanized her. Mind you this is an elderly woman who just lost her husband. I phoned mtn asked to speak to the manager to bring such behavior to his attention and to get Sylvester to call and apologize to my mother. He did call me and he was sarcastic and with a laugh in the mix. I then told him if he thinks the situation is funny I will report this matter I was and am furious! He then phoned my mother again back and forth conversation that had no apology. I am disgusted by this. Do you treat every elderly person this way? What is wrong with you!