Kesari Travels — No refund given of Europe tour

My parents booked europe tour and paid full amount in dec-2019, but due to covid it has been cancelled. But no updates post pandemic. No news on refund, no response to mail. Absolutely zero touch point with customer. First time my parents supposed to travel through Kesari Travel, but it was unexpected. My parents are senior citizens and don't want to travel in future also out of India. And money they paid is their retirement fund.