Account "short paid" but no record

On 16 Feb 2017 i got communication saying my account has been "short paid" for many months and that it accumulated an amount that needed to be paid asap or my services will be suspended. I was back and forth with them and eventually got it sorted and i was given a "new" amount to pay per month which i did. Ironically, almost a year later... 29 Jan 2018 i get communication saying my account has been "short paid" for many months and that it accumulated an amount.. (same sh*t different year). No where on my statements does it show the account is behind... in fact, on my January statement it showed the amount due with (-) infront of it. I am really getting sick of this... Can i take this matter further???