Issue with additional parking in redevelopment

My building has gone for redevelopment. As per the agreement with the builder all members having stilt garage will be given one additional parking. The stilt mentioned in my agreement was not alloted to me and given to the owner and I was alloted another stilt which I am in possession of. The owner has partioned half of my stilt as well and now claiming one parking in lieu of the redevelopment The Managing Committee is saying as this is disputed they cannot allot me a parking space in the proposed society in lieu of the redevelopment and favoring the owner. For all other owners having stilt the additional parking is mentioned in their agreement but in my case the managing committee is saying that since this is disputed I cannot claim additional parking space and if I need the builder will be allot on basis of allotment letter. We have vacated the building and the managing committee has withheld our monthly rent received from the builder asking to sign the PAA otherwise cheque will not be issued In such scenario what are my rights to claim the additional parking and also ensuring that I receive my monthly rental cheque Should I send a legal notice to the managing committee as they are illegally holding my cheque ?