account in arrears but no statement sent

I did not get my dec 2019 statement, I requested that now in Jan 2020 as I did not know how much was due, the statement was sent on the 06 Jan the next thing I get a rude phone call from their consultant that my account is in arrears, I asked how as I did not get the Dec statement so how much was I to pay. I asked her when was the Dec statement sent, she said their statements are sent on the 7th of every month, I asked when was the Dec one sent as I even sent an email in jan requesting the dec statement, she said she cant answer for other consultants her call is to make an arrangement with me to pay. I refused saying I will not accept my account to be in arrears due to them not sending me the statement in time and now want to send me statements for Dec and Jan at the same time and make me liable for the arrears, she said she doesn't work with sending statements so she cant assist me with that query, I need to make an arrangement, I told her someone has to apologies for not sending me the dec statement and on that letter confirm that my account is not in arrears, I will pay the dec premium at the end of jan and jan in Feb as that is their fault and they will have to make sure that doesn't affect my credit profile. the consultant that called me is very unprofessional(Nonkululeko). Last statement received was on the 1 Nov 2019, the following statement sent on the 07 jan 2020 after I sent a request on the 06 Jan, now I am being told my account is in arrears, again I have not been sent the Jan 2020 statement but I am in arrears, wow!!!!