Payme India — Auto debit

I'm just confused why is pay me india loan app trying to do 8 times auto debit on my account in one month, Now I'm paying 8 Ach debit return charges to my Bank.. Bank staff told me that AcH auto debit should be try once and if insufficient balance then also only person month auto debit should be try.
I need help. Auto debit 8 times in a month due to insufficient balance is legal or illegal?? Someone pls help me.