Poor service form Tshwane Municipality

It is since February 2019 that I have request Tshwane Municipality on a monthly basis to update my email address to my new email address. But after 7 months they are still not capable to do a simple admin task to change it. My statements are still sent to old email which means I am not able to receive my monthly statements. I have even received an email of confirmation that my email was updated, but it did not happen. I don't know what else must I do to convince Tshwane Customer support to "SUPPORT" me with my request.