I need my contract cancelled

I signed up for a Mondo Telkom contract in March, I was told the contract came with minutes which is exactly what I needed, Mondo was very quick to debit the admin fee, it took an additional month for the phone to arrive (considering we're under lockdown, I didn't see an issue). After the phone was delivered, it took an additional few days for the sim to be activateed. To my surprise, I couldn't make any calls, I did some research on the contract and realised that I could only call telkom numbers with the minutes available. If I was told this at sales stage, I would never have taken the contract, I was under the impression that it was for all networks. I called Mondo and was told their hands are tied but I should call Telkom to see if this can be changed. I couldn't get through to Telkom. I have e-mailed Mondo as they requested for the cancellation of this contract as this is not what I had agreed to, I haven't heard back from them, I need this contract cancelled and the phone to be collected. I would not have agreed to this contract if I had know that I could only call telkom numbers with the minutes available. I will rather still with cell c as they have packages to better suit my needs. I am still working and can only be reached after 15:00 during the week, alternatively, you can contact me via e-mail. Thank you.