Herotel the bully

Service was cut of after call out, they told me there would be no callout fee. Then i received an invoice for R500 telling me they will cut my internet if it is not paid immediately no time frame given of when it will be cut of. Today they cut of my internet without warning im still negotiating with their accounts department as i feel i dont owe them the money. My month internet is psid for but they still cut of my internet. Herotel another big company bullying their clients to pay up and shut up or we just cut off your service.