The cancellation email is hidden deep in their T&C's section. Did you mail that one?
[email protected].
Official Supersonic Terms and Conditions for uncapped internet services in South Africa. Transparent policies on billing, cancellations, fair usage and consumer protection.
supersonic.co.za
Supersonic Home Broadband F-LTE Terms and Conditions
Section 12
View attachment 1208232
Once they get the mail, you can wait a number of days before a response...
EDIT: PS, this is the only way to cancel your LTE. I asked them why they don't have an easy cancel button in their client zone and let them know that finding the bloody email address was convoluted.