Vodacom incorrect invoice and billing impacted my credit record

Requested Vodacom to provide me with an early cancellation invoice. While this was swift and easy, payment was shortly made in full (stated amount on the invoice) Month end comes along and collections calls me to pay R3900+- because I've short paid, after telling them I paid what was sent to me, and in full. They ensured me the payment was received, but there's an error and I need to pay the difference!

Now i've been on their line for hours and the lines drop, or it's so loud that i can't hear the consultant. They start getting cheeky because of the loud environment and drop my call. Moving my query over to Tobi, made even less effort or difference. Vodacom has noted that i've been marked as a late payer due to their mistake and billing issues.