Poor customer service received at game Brooklyn

Hi recently bought a generator in game Brooklyn when I started it didn't want to work so send it back for repairs or my money back they failed to assist me they called their manager JP who started shouting at me calling me cheecky so I reported the matter to the head office but still didn't get any response as to what is the way forward since I can't go to their store because JP the store manager threatened to escalate the matter outside business it has been now two months they have my generator and not contacting please help.