Vodacom Fibre TRASH!!

I cancelled my Vodacom Fibre line in May and i was on a MONTH-TO-MONTH line, everything when smoothly with the cancellation, BUT, after 2 months they send me an invoice for that line. When I called in, they told me that it's the balance of contract with it can't be because it wasn't on a 12/24 month contract. I was also not informed of this amount that would be invoice and apparently according to their system an email was sent, which i didn't receive, i received every other email from them but coincidentally not that one, only after i spoke to them, they sent it. They also said that someone will call me regarding this matter but yet it's 2 day's later and nothing. Yet if you fight this, they just won't do anything because they know they have TRASH service and it effects your credit score! TRASH!! TRASH!!! TRASH!!!