Accounts Department can not do accounting

I have opt for the price lock package last year 2016 July. Since I have taken out this package there were always a problem with my account showing that it is in arrears. After multiple emails sent to the accounts department with no replies, and numerous telephone conversations with the client departments they still can not resolve my account. Every month they disconnect my services, only stating that my account is in arrears. After making cash payments on this account they only tell me that I am behind on the price lock account. I have shifted money over into that account to bring it up to date but the problem don`t get solved. I have downloaded my last statement of July 2017 and it does not show any arrears. These people working at their accounts department are unprofessional and it puts their whole business in a very bad light.