Stage zero - huge red flag

I am being told I owe over R400. I do not. I have the email confirming outstanding is R0. Yet I am being harrased with communication to make payment. The company does not seem to know what they are doing. After canceling a ups ( which was from frogfoot/vox) and getting confirmation, I kept getting contacted by somone from the company to log into my custimer portal to cancel. I dont have a customer portal... never did. When I tried to create one, it would not let me. Finally I get contaced back to say they see its been cancelled - staff are not great.