Devagara builders maussori wood apartment - Delay in handing over flat

Hii, myself is ex-servicemen from haridwar and I had a deal with builder last year for * bhk of INR **.** lakh at dehradun, i have paid INR *.** lakh cash and taken loan from SBI for INR ** lakh in the month of march ****. Balance amount of * lakh is decided to be given on possesion. From April the builder is not attempting to finish the remaining works pending in flat for a possesion, and giving an excuse of pendamic due to covid**. I offered him the deal several time to hand over the flat is present condition as I'm ready to complete remaining works on my own with my expenses. I'm presently residing in rent and due to non readiness of flat I'm loosing my hard earn money of INR ***** per month as a rent as well as EMI of ***** per month against the home loan is also at my financial stack. that the remaining work .
Fitment of doors and internal painting work along with small makeover works are pending since March and the builder is unable to finish that work within promised time frame. Those works can be taken by at my expense and the same has been conveyed to him but he resist to listen and thus costing me unnecessary loss of hard earned money towards rent I'm paying where I'm staying presently. Moreover due to this I'm not able to takeover the offer of job from my employer as I have to fly abroad for the same if I take the offer. Need help to take over the flat in present condition while Subtract the amount of remaining work cost .