Poor customer service by accounts department

I had a car tracking device fitted on my car December 31st, everything was fine and a debit order was going through on the 27th of every month till March before the national lockdown whereby their debit order went twice on my account and I disputed 1 since I only subscribed for 1 vehicle. The problem started monday when I got a call and an email on Monday informing me about my overdue account which amounted to R1200 and i will be liable for collections fee amounting to R1800, was given a number to call the but no one seems to answer the phone and my emails are never respondent to as I want clarity about the overdue amount on my account.