Pre-paid cellphone number deleted with airtime

I am very disappointed with Vodacome. My Granny has had a Vodacom cellphone number for years and used it when she was out. She has been unable to use it for the last few months as she has not been well. On Thursday she needed to use it as there was a problem with her Telkom number. We were advised by one of her neighbours that her cellphone number was not working. When we went there on Thursday evening I tried the phone and a voicemail said this number no longer exists. I was unable to do anything with the number not even transfer airtime. I called the call-centre yesterday where I was advised that the number was deleted. This is unexceptable as there was still airtime on the phone which she is now unable to access. My Granny has requested me to ask you to either re-create her number or pay out the airtime to my number. She says there was approximately R70.00 on the phone which she would like back. I have told her that I cant promise she will get her airtime but she is not interested. She said she wants it to come to me if her number can not be retrieved. Her number is ***. I would really appreciate a response as I don't actually know what more to do.