Maintenance for apartment for period between date of registration and date of actual possession

Hello I purchased an apartment in 2017 and entered into an agreement with builder. Towards the end of project I registered the Sale Deed for the same without completion of all work in Feb 2020 based on promise that actual possession will be handed over within 2 months. But once lock down were placed due to COVID builder didn't completed the apartment work. Also in the meanwhile I got transferred to a different station and builder didn't proceeded with any work for many months and finally handed the possession of flat in July 2021. No formal letter is also provided for this hand over of possession is given. The occupancy cetificate for the building was issued in Sep 2021. Now I am being charged maintenance charges for common amenities from the date of registration and during take over of building amenities by RWA I am handed over letter that I need to pay the dues amount. Is this correct way of charging maintenance fee? Since RWA has agreed for maintenance from date of registration I want to understand my options without affecting relations with co-owners in the society