What legal action can I take for delay in property handover?

I purchased an apartment in 2017 with a completion date of Q4-2018. Till now, the construction is not complete. And based on the construction update, it will not complete in 2020.

As per the agreement I already paid 50% of the amount and rest 50% is due on completion. As per the Default and Termination clause of the SPA, I sent the notice for termination on 5th Jan 2019.

This clause clearly states that "If the seller has not served the completion notice within a period of 12 months from the anticipated completion date (unless the delay is caused by force majeure) and the purchaser has fulfilled all of the purchaser obligations under this agreement, the purchaser shall be entitled to send a written notice to the seller requiring the seller to complete the building works within 90 working days of receipt of the purchaser's written notice.

That time has elapsed and now I have to send the second notice as the remedial period of 20 days is also coming to an end.

Please advise on the plan forward.