I paid up my trackin...

I paid up my tracking device contract with them from 2021 to 2023 they sent me confirmation that it was paid up and cancelled in 2023 suddenly in 2025 I owed them an amount of R156 to which I paid because I dont want issues and talks now they refuse to send me my paid up letter because in the next 2years they will do the same thing again! They are ****mers and their call centre agents dont know anything and can't answer any questions