Can we cancel signed bba/ cancel allotment where entire bsp has been paid

Bought a 150 sq.ft lock n key office space on 4th floor in under construction assured return project with MOU date 29 Jan 2012. Paid Entire Basis Sale Price of unit. Assured return stopped coming soon after. No progress in construction. No response from developer. Filled case with RERA Gurgaon 20 Mar 2018. Nothing came out of it. Till this date, there was a bare shell of building with little or no construction. Later, builder informed us that they have shifted our 4th floor space on 1st and 2nd floor. Left with no option but to sign an agreement dated 18 Oct 2019 agreeing to shift to 2nd floor 160 sq. ft customized/managed office (to be constructed) space.

On 12 Mar 2021, while I was out of Delhi, my father signed a BBA and lease agreement on developer verbal promises. Due to covid delta strain, it took months to get hold of physical copy of BBA and LA. I am beyond words of what all clauses they have put. It states we cannot receive physical possession of the space. It will solely for the lease purpose. The space will be clubbed with other spaces for lease. The developer has fooled us from having a lock and key space to an open floor plan where your space does not have a physical existence. There are n number of charges being put. We will have no say in whatsoever except for paying maintenance and allied charges as well signing and accepting their endless list of agreements.

I want to cancel this BBA and lease Agreement as this was done by creating a false pressure my father. How do I go about it?

Secondly, there is a clause of cancellation of allotment at sole discretion of developer by forfeiting the earnest money of 15% from the amount refundable to us. What measures should I take to ensure that we can get our money back and cancel this allotment?