On Air TV billing false inaccurrate claims

After having completed a two year contract with On Air for the DSTV explora, almost a year ago, they continue to send sms notifications that the account is in arrears and threaten to hand us over to attorneys. I have contacted On Air on two occassions post the contract ending period and have not obtained a valid reason for additional claims beyond the official contract period. This is absolute *****ulent behaviour and is typical of how honest paying south african people end up with a bad credit rating due either incompetence by the business staff or as mentioned, *****ulent and ******* billing. They repeatedly say they will resend us a statement which they never do. How many other people are being subjected to dishonnest billing by On Air?