Make my trip - additional charges for date change it can be happened free of cost

i booked ticket of mumbai to chennai for * passengers on ** of july **** which cost me ***** rupees after booking i noticed passenger middle name of third passenger was wrongly edited so i immediately called make my trip website for correction so they said we cannot change the name then can forward request to airlines regarding this and then i again asked to confirm the same then they said airline will not allow so i asked for the solution on this for cancellation then they said this is non refundable but as per airlines minestry tickets will be cancelled within ** hrs with full refund amount they miss guide me and did not tell me about this instead they said we can change the date in which new name will be updated of the passenger and so i raised a request to reshedule or date change the i called back make my trip then they said u will get new tickets on **th in which you will get it updated in *hrs i got new tickets and no changes were made on tickets only date were changed and i was charged **** rs for date change which can be done free of cost within ** hrs but still i was charged **** rs i have got one notification of make my trip itself on whatsapp in which date change can be done free of cost so my concern is why did they charge me extra amount for date change it could have been done free of cost i want tha amount to be refunded again now they say our senior will call you back but no one call back every time they say seniors will call back still no call from their side.