Transgression against CPA

I took out a contract on Sunday 03 December 2023. In accordance with s16 term of the CPA I wished to return the device for a contract cancellation on Tueday 5 December 2023, only 3 days later. Legally they were required to cancel my contract and give me a full refund of any fees with no penalty besides a possibly small penalty for unboxing. The manager at the westgate branch near game with the name Chadwin, refused to cancel my contract and turned me away. When I called their online store to query this the woman informed me that there would be a hefty cancellation fee. This goes directly against s16 of the CPA and infringes my rights as a Consumer. I am attempting to go back to the store today and request a cancellation for the last time before progressing this to the NCC.