Withholding Refund

Extremely disappointed that companies like travel start are actually withholding refunds and making money of people's cancelled trips in a time like this. I had flights booked for my manager and his partner through travelstart and have numerously requested a refund its been almost a year. I have contacted Mango airlines who then informed me that the refund would have to be done directly to travelstart and than refunded to me. Travel start has pointed that a refund isn't possible. I've tried calling and emailing with no success. I cant accept a credit or postpone flights as the guests do not wish to travel. Other platforms such as expedia, flight center etc have no issues with refunding their clients so I do not see a valid reason withholding funds