Mhada — Mhada flat priced increased Shirdhon 270

Hi,
I was selected for mhada lottery code 270 in 2018 and the possession date was 31st March 2021. But due to covid the construction work is still in progress and now suddenly they are saying that the prices of the flat which was mentioned in 2018 is increased and also the completion of work will take more 9 months.
So wanted to ask is this our fault that the work is not completed on time and fyi the work is under Shirke builder which is doing both cidco as well as mhada work and there another project of cidco in kalamboli is nearly completed which was actually started after mhada work. So what is this all going on.