Termination of an off-plan property SPA and getting a refund

Hello,

My father had purchased an off-plan hotel room (rental-pool) in Dubai. He paid the deposit and all fees and has been paying all installments on schedule towards the developer's escrow account. However, the project's ACD was on June 19, with the six-month extension, Dec '19.

He stopped paying the installments after the extension period (paid around %65) on the grounds that the project is yet not running and not generating him any revenue. According to the DLD, the project reached 100% completion on October 20.

He asked the developer to cancel the SPA after the extension period, but they kept stalling and saying it is not possible. Moreover, they provided us with different dates for the ADC. The SPA says June 19 while the Property Reservation Agreement says Dec 19.

Due to financial constraints, he cannot continue with further payments. What is the possibility to cancel the SPA through the DLD or Real Estate Courts in Dubai?