Information update

I have been to the Vodacom in the Pavilion Shopping Centre for I think 3 times to update my address and surname. Each time I go there they say its updated but I have never received a invoice with the correct surname. I only received the correct address once. Now I have 5 invoices and all the addresses are incorrect plus the surname is still incorrect. Even with the paper work in front of them they still can't get it right.