Cell C Cancellation policy.

Hi, i had contracts with Cell C for many years now. I tried to cancel the last one a had with them on the 24 Feb 2023. They told me it is too early and i have to call on the 28 Feb 2023. With me busy life, i forgot to call on that date and called again on 06 March 2023 to cancel since the contract expires on the 31 March anyway. Now they want me to pay at the end of March and again at the end of April. If a contract expires, doesn't it mean that it is finish, why do they not just cancel the contract? Why must you give 30 days notice? Who signed a contract for a specific period and when it's done and you don't want to continue, it should automatically be cancelled. . They just know how to rob the people. I will never do business with CELL C again. They lost a valued customer.