I paid for an empty gas Cylinder which wasn't filled at all!!

Am highly disappointed with their services, in fact am so exasperated as in now....On the 11th of April 2021, which was a Sunday morning l visited the store to fill the gas on my cylinder. A week later when l needed to use the gas, there was nothing blowing. And besides after refilling there wasn't any difference. And it never triggered me cause am not well advanced on this. When l went back to let them know about the issue a week later for l hardly use the gas as its meant for emergency, l was told to have brought a slip and they're yet to investigate the matter on which grounds cause the cylinder is empty its not like they cant weigh it. Am ****ed and like hell... I won't recommend anyone there not even......