Long overdue refund from Qatar

Last week I wrote to Hellopwter seeking assistance with my refund that has been held by Qatar Airways for no reason. After writing that review they called me and promised to resolve the matter, but after that they kept quite. I tried to send several emails and no one is responding. Please help I need to know which channels do I need to follow so that I can get my full refund from Qatar. They cancelled their flights but still refuse to give me my refund.