Refusing to refund reservation down payment upon cancelling a unit

I was in a process of buying a property in Dubai from a developer.

Their sales representative advised me to put a deposit of AED 10,000 to reserve the unit. We agreed the value can be fully refunded if I cancelled within 10 working days.

A few days later, I requested to cancel my reservation and refund my money back. They refused to refund my money back.

I have supporting documents which prove my agreement with them in the form of:

- The email in which I reserved the unit list the terms & conditions (which I have written)

- I have an updated payment form from them and hand wrote the condition of unit reservation (full refund if cancelled within 10 working days)

- Exchanged WhatsApp with their sales representative.

They claim that the above proofs are not enough to support my claims, and so they are refusing to refund my money back.

Please share your thoughts on my email [--------------------].