eDreams complaint: refund

Dear SirMadam,
Please help me.
I bought a ticket from Edreams on 15th March. I canceled this ticket within a day, then they said I would receive the full refund in business 7-10 days. I waited in 10 days and did not get anything. I contacted them so many times (i cannot count), they said they sent the refund request to the airline and I would receive it in business 7-10 days. Every time I contacted they said that. I contacted the airline, the airline said that the agency did not do it. Then I contacted the agency, they still said they did, the airline said they did not. I contacted the agency again, They said that the agent forgot to cancel my flight and they would fix this issue. I checked 2 times in 2 weeks. The agency still said they did, the airlines still said the agency still did not do any thing (no cancelation of my flight and the refund request) until now
Please help me.
Thanks a lot.
Best regards,
Hoa