StashFin — loan:- payment made but showing overdue charges

Address: 245101

Website: www.stashfin.com

I took a personal loan from stashfin (Basiclly i doweload this app for stashfin card & eventully they disbused this amount but now feel lucky coz they are useless) of rs - 1000, for that emi rs 1200 payable on[protected]. While i paid emi on[protected] but no record updated on stashfin app due to that they are continously calling & msg me, on app overdue charges are also showing.
Their help line no. (Not working) i send lot of time screenshots of mpassbook but they never reply
Kindly help me becouse on call they are threating to report on cibil.