Complaint against Vodacom about a contract that was cancelled on Cell Number ***

Good day, I am writing to complain about Vodacom, they were notified in May 2020 about a contract cancellation for cellphone number ***. This contract was in my son's name who resides in the United States. The number was ported to another service provider when contract ended. Vodacom was given one month's notice about the cancellation and debited my son's account after the contract was cancelled which he reversed. I sent numerous emails approximately 20 emails to various departments at Vodacom such as Subscriber Collections, Retention Collections, Vodacom SA, their collections department, as I started receiving calls from their Collections Department and now from Attorneys. Vodacom requested an Affidavit regarding the matter, as well as a letter of authorization from my son which was mailed to all the various departments. I am really disappointed in Vodacom constantly hounding me by calling my son's old number advising that the matter is handed over. I've asked them in the emails to verify that they have received all the relevant information about the cancellation and to advise me when the matter will be resolved. I'm shocked as I received another call from attorneys today. Please can Vodacom rectify their records and stop harassing us for payment for a contract that was cancelled.