loan emi failure of payment

I had availed loan of Rs 95000 from kreditbee app. My 5th emi du date was 5th august. But I failed to pay that due to my bad financial conditions now. I told their agent that I will pay emi but it will be paid within next 1 and half month. But they are not listening and harsaing through calls. They called my reference also and used harsh words. And today they called me and said pay before 3 pm otherwise legal notice should be issued. What to do now? I can't pay emi till 20 th September. But they keep harassing. What can I do?