Byju's — Not refunding extra emi

I have bought byju on emi basis for 12 months, but my emi has to be ended on august even then byju debit money from my account in September, I have been calling them, emailing them, talking to mentor from past 1month they are just making me fool that they are working on it and will credit it
soon within 24 to 48 hours but like this they have wasted my one month and till now they have not refunded me .which is very bad I am tired of writing them again and again 😡 soo plzzz refund my money asap