Nedbank threatening people even though they don't have an account?????

Worst experience ever. I keep on missing calls from Nedbank as I am at work and have not had an account with them since 2019. I did however receive a call from them stating that I owe them money as my account is overdrawn. WHICH ACCOUNT??? I closed my account in September 2019... And when you try and call them back after you receive a threatening message stating that the sheriff will be coming to either your office or home? Really Nedbank? This is how you do things? I reported the issue stating that the account was closed and waiting for feedback, yet now I receive this? You are ridiculous!