Exuberant interest on property

I've booked an apartment in affordable housing in august 2019, and the possession of the apartment was promised by December 2019. Due to Covid19 breakdown, the possession got delayed and even I was not able to pay the installment amount on time. Due to non payment my apartment allotment got cancelled. Upon request from the Management of the builder team, the unit was reallocated to me after I paid the called amount by getting a bank loan in the month of August 2021. The RERA licence of the builder got expired by this time and he further delayed the possession. I recently received an email of possession from the builder, which was further delayed. Now they are asking exuberant amount of interest on possession. I've already faced a lot of financial loss on this apartment due to delay in possession. now I cannot further afford to pay any such interest. Could you please advise me, if there is any possibility of getting the interest waived off, or taking any legal action against the builder for delay in possession.