EARLY DEBIT ORDER

I have a loan with the above mentioned bank and my debit order date is the 19th each month.On the 12 i received an sms that i need to pay my loan as in arrears.I got a call from the agent that i need to make payment i asked why as my debit order is only a few day away.I told her i do not appreciate thatcall and to date i have 6 messages that if i dont pay this will after my credit ratings.why should this be the case as i pay on the 19.The agent have the nerve to tell me that in DEC they do early collections,why early collections as i only have money on that date?Arent they supposed to check with me if i do have money by those dates?Can somebody fix this as I DONT WANT TO RECEIVE SUCH CALLS AS IM NOT IN ARRTEARS!!!!!