Sim Card and Number Deleted

I use a prepaid number from Vodacom for my emails and noticed that my emails stopped working. Inserted the sim card into a phone and saw that the number is inactive. This has happened in the past and I phoned the call center so that they can activate the number and get my emails working again. I have been using this number for a number of years and constantly have to go through this inconvenience. The call center representative Granny was not helpful or friendly at all and refused to give me a reference for the call. Vodacom no says that is it impossible for me to get my number back. This is utter nonsense as I have gotten use of the number back in the past. I don't understand that it is not possible to make a note in the system not to delete or make this number inactive every few months. Surely they can see that the mailbox linked to the number is being used.