Rental dispute during covid

I have a 1 bhk flat in Thane. A tenant had blocked it with deposit and advance in Feb but made the agreement for March 15 only. We waited till then. But even then they showed no signs of shifting. The broker told us they wanted to shift only in April. But immediately after the lockdown was announced, they used that as excuse and sent me a mail saying they could not shift because of lockdown so we had to adjust the rent. And start charging only when they move in. When I reminded that it was they who delayed, they started giving false excuses like the house needed more work to make it 'livable' etc and started demanding extra things to be added. I refused whatever they demanded after registration. Whatever was agreed before registration, I had fulfilled. Now what should I do? I would suffer a loss for several months now for no fault of mine. I'm even willing to exit the agreement seeing their nature, but I have spent on brokerage, registration etc. That's another loss. Unable to find a way out.