Can you sue the developer after failing to hand over property beyond grace period?

Dear, good day,

The developer failed to hand over the project by Mar 2020 as per the SPA. Installments were paid on time, he is in dispute with his construction contractor.

He wanted to change him since there was a fire at the construction site, however, the authorities granted permission to resume construction after the investigation is finished last year.

The developer still to this date failing to terminate the defaulted old contractor and appoint a new construction contractor which is causing a delay.

I have requested termination of SPA and claimed a refund but was declined. The project construction is still around 30% since more than 15 months where it should be 100% back in Mar-2020.

There is a clause in SPA to grant 1 year and 90 days (remedy period), I have sent a written notice to claim a refund as per the contractual clause and time frame.

Could you please advise what are the steps and chances to push the developer to refund full amounts? Should I start with RERA first?

Thanks in advance.