Insulted, mocked and humiliated at Eastgate by a staff member for refill the gas

I went to Megapaints Hardware in Eastgate to refill the gas. A guy by the name of Rofhuwa was the one assisting the customers. When he got to me I kindly asked him to open the cylinder for me as I struggled to open it. Wow the guy started swearing at me and thrown the unthinkable insults at me so much so that the other customers tried to rebuke him but he continued. I apologized for asking for his help more than 4 times but he just couldn't stop screaming and yelling at me and said he will not assist me even if I call the Manager . When I told him I will report the matter to his Superior he clearly stated that he was not afraid of any of them. I went to the Manager Mr David who said he will resolve the matter but clearly he is afraid of this Rofhuwa guy because he later came back to me with the empty cylinder and told me that Rofhuwa said there is no gas. The customers who came after me were assisted