Incompetence

I'd like to understand why after over a year my contract concluded with this people and gave them a 30 days notice prior that I will not be renewing, they have the nerve to send me an email claiming I owe them R249? I've been getting whatsapp messages from their sales consultants as well pestering me to come back but this is absolutely ludicrous. I don't ever want nothing to with Moove company or Moove Cosmo City after this.