Builder annexing car parking allotment with maintenance Due

We procured flat from a reputed builder in Chennai and they were maintenance for several years and we used to pay it on time but several years back in 2017 they suddenly stopped maintenance and sent arrears invoice for several months to owners out of blue claiming it's due. We questioned builder for this sudden invoice and high amount but they are not ready to listen and keep adding interest. Later the maintenance was taken over by owners association and we have been paying to them without any due. We had bought car parking when purchased flat but the builder didn't allocate a car parking number during handover and now they have annexed the pending car parking allotment to pending due and telling since Maintenance due is pending they are cancelling our parking and forcing us to pay pending due with 18% interest. 1. Can builder send past maintenance invoice suddenly to all owners claiming it's due. 2. Can he annex the car park allotment to pending dues. Also they didn't allocate car parking during handover since they over sold the car parking and there were issues to whom they will allocate. Later builder got a revised DTCP approval with more parking by reducing the road width by few fts. 1. Can builder revise the DTCP without the 2/3 consent of the owners since most of them already accoupied and started living for several years. What should we do in this situation as the builder is claiming several lakhs due by adding interest for the past 7 years, it was 65000 in 2017 but in few lakhs in 2024. Also they are not giving our car parking allotment. Kindly guide.