Cancellations are done by phone contact etc to prevent unauthorised cancellations.
Best to ring 132200 and say "Cancellation"
A "Like" is always appreciated. If my advice is a solution, please mark it. I'm not a Telstra employee. 50 + years exp. in radio comms., eg mobile phones since 1963, two-way radios, base stations, antennas & pagers. "Being 75 years of age, entitles "you" to be an expert at everything!!"