Tata Motors Finance — changing the emi date

I want to change my emi date, , now is 02, , but I want this, , 09 per month // I call to toll free no. but he told me that, , , we can't change the date now, after 06 month, , , , , , , , but why, I m not comfortable for the date 02 now, , my cheque are bouncing, , , and i m paying the penalty charges, /// so pls change my emi date, thanks