Dishonest and not owning up to mistakes

I booked flights through Booking.com. I phoned to merely enquire about the cancellation policy and next thing my flights were cancelled - they made me believe that the airline cancelled the flight and gave me a voucher to rebook the flight. There was over R2 000 difference between what I paid Booking.com for the flight and the voucher issued. Remember, I did not request the flights to be cancelled, Booking.com cancelled it unilaterally and without my consent. I contacted the airline and they confirmed that the flight was not cancelled from their side. I'm now trying to claim my R2 000 odd back from them and have probably written 10 e-mails and gotten the same response every time namely that.... since a voucher was issued, they cannot help me with a refund. They are not owning up to their mistake and I feel ******. I have been using Booking.com for many years and am on Genius level 3 already but I will not use it ever again and will advise, friends, family and business colleagues not to use it. They are dishonest, I cannot do business with a dishonest company.