Swearing and insulting

This lot called me about aircon repair I missed the calls so called back. Some guy called Mohamed or similar answered I asked who it was and he started shouting and carrying on like a lunatic He told me there is something wrong with me and slammed the phone down I called back and the same person started shouting again and told me to **** off!!! I called again and spoke to somebody who is supposedly a supervisor but he doesn't know who it was so he cant do anything! What a lot of aggressive people . Shouting, insulting and swearing at people What a way to run a business