Opodo review: Cancelled ticket refund - will not return money

I bought a ticket through Opodo to travel from London to Shanghai on Air China. The airline had to cancel the ticket and did not offer an alternative solution.
Opodo did nothing to help me find an alternative journey. After spending over 2 hours on the phone with them, I asked them to cancel the flight and offer a refund.
10 days passed and I never heard back from them. I contacted the airline and asked them to cancel the flight, which they said had to be done by the agent. Again, I spent 1.5 hrs on the phone with Opodo and finally managed to speak to someone who said they would cancel the flight.
It has been another 10 days I still have no reply. I contacted Air China again (long distance call to China) and they indicated that the flight has been cancelled and the refund issued.
After another 57 minutes I finally managed to speak to someone at Opodo. They tell me that I now have to wait 30 days for the AIRLINE to refund the tickets, even though I have proof from the airline that the flights have been refunded already. Opodo refuse to return my money.