Air India — reschedule link extra money not send and pay extra

I booked air india flight on 25 mar 2020 for delhi to patna for 16 apr 2020 with pnr no. Is ywdnn. But due to covid-19 flt was cancelled when i call to customer care on 16 apr 2020 for reshudle my flt he tell me in 10-12 hrs call back from reshudle department but no call coming from that side i again call to 17 apr 2020 he tell me in two hrs call back to you but no call back from that side again i call on 18 apr 2020 then he tell me i reshudle your flight for 09 may 2020 but some reshudle charge may be paid but when i tell him for send me payment link he tell me i sent but he didn't sent mail. Again i call to another representative she tell me i don't sent u link
I don't understand what r doing air india. I understand that this is totally frauding for payment increased. Please resolve my problem