Terrible noisy staff with support from their supervisor

Today I had a terrible experience from McD cradlestone Mall, I was sitting outside enjoying my meal and some staff members came there and started to be loud for no reason, too loud in an annoying way. I reported the matter and the supervisor on duty told me that he can't tell customers how to talk. My reply was, if it was customers it's ok but not staff and why would customers shout??? The staff there lack respect for customers, totally not right. If I wanted food from a taxi rank I would have went there but chose my peace and quiet... It was my first time there and this is what I get.... Your supervisor is so rude. I was there around 13h30 today.