I NEED A LETTER STATING MY ACCOUNT HAS BEEN CLOSED

Been involved in an accident,and my car was written off and was told my account is indeed paid up as my insurance sent me the proof of payment,i'v been caling MFC to request the letter stating that my account has been closed,but i still get nothing,i need to use this letter but im not sure whts taking them so long,im tired of waisting my airtime on them,i need that letter ASAP