Not delivering on a request to cancel a line rental.

In general, I am satisfied with Vodacom's service and delivery.

However I been billed for a number I tried to cancel, the call was made and after much struggle, I got through to a call center agent who could assist.

In late 2017 or early 2018 I took an S9 package where a free phone was given with the contract. I sold the extra phone sealed in the package.

Fast forward to the next upgrade and I get the S20+ package, however I am now been billed for the line rental for the free phone. (066 *** 3328) I called to cancel the service for that number and after a few bureaucratic issues eventually got through to someone who could assist correctly. At the end of the call he confirmed that the number would be cancelled. (I cant do this as I was never in possession of the sim card.) I was also informed of a special whereby if I extend my contract for an extra three months there would be some sort of cheaper rate (Cant remember the details)

For the duration of the package that came with the phone the line rental for the free phone was not charged on the old invoice. When the contract ended the line rental started to be charged for. I can understand this and have no argument. But I have called to cancel that service and wish to be reimbursed for the latest invoice.