Vodacom deleting my number

I've had my number with Vodacom for over 29 years. I recently moved my account to prepaid, despite the phone being used, despite having a very healthy credit balance on my prepaid account, despite it being topped up religiously on a monthly basis, Vodacom just decided to "delete" my number, no notice, no warning, nothing. Their response, sorry, they can't reactivate the number, I need a new SIM card.