Simpl Pay - Wrong EMI shedule with penalty

On sep **th **** | purchased a watch from Myntra and selected payment in EMI mode via
SIMPL pay later option. *st intsallment paid on sep month itself and next two installments on oct and nov**th.presently on **th oct | opened app to pay this month installement but they clubbed both oct and nov month at a time and showing to pay full amount which is against they showed me.l contacted their customer service explained the issue but within the time of thier response I was charged penalty on late fee from them.I want to pay only oct month installemt but they were showing at a time full amount now added penalty. Customer care said that it was a glicth and will waivoff the penalty, but till now nothing happened,they just saying ticket resolved.My penalty would increase because of their fault and lam helpless and dont know whom to contact.Company name:-SIMPL address:-Diamond district ISRO colony bengaluru
******