Faulty meters and unfairly billing customers

Prestige is the metering company responsible for installing electricity meters at the previous flat that I lived at. Upon moving in Prestige did not come through to check our meter box to ensure that everything was in order. A few months later they send someone through to our flat under false pretence of "maintenance". This person comes through and does something with the meter box so I send an email to inquire only for them to reply to my email weeks later with a bill of R6289.49 which they demanded I pay within 3 days. They claim that the meter was bypassed. I don't see how that was my fault as I didn't bypass the meter and it should have been check when I moved in. They installed it and used this method to make money out of the tenants with the threat of disconnecting the electricity and water. They have no remorse towards their clients and everything is about making money. They are ********* and left many tenants in major financial issues.