Account Handed to Debt Collect while not in arrears

Account handed over to debt collectors while the credit life insurance has paid a lump sum for 6 months instalment due to retrenchment. Credit life insurance paid instalments for period Jan 2022 - June 2022 but Standard Bank decided to hand over account to debt collecters; under which circumstances i don't know and when trying to engage them i am passed from one person to the other. Account not in arrears but i am getting calls and sms's from debt collectors almost daily.