Mistake made by COJ and we must pay???

Since September 2018 I am battling to get my account corrected . Several visits to COJ offices resulted in no action. Although I was promised in September that this query/account would be corrected within 3 months. We are now more then 8 months further and still nothing has been done by COJ. Now we are threatened with legal actions and discontinue our services.. For a mistake COJ accounts department makes??? Ref no ********** 586