Promises not kept at my expense

Yesterday I had extra airtime and data that expired at 23:59. It vanished before I could use all of it and called the contact centre 22:13pm to understand what happened. Nonhlahla from call centre servicing Pretoria told me I could only be assisted once the system updated. I asked if this will be done by 23.59 and he said no, then I asked what will happen to the remaining airtime and data which will expire soon, he insisted I wait for the update, only then will the remaining airtime and data be credited to my number and he will call back once it is done. I requested him to call back at 5:30am (convenient time for me) as I was going to sleep and it will still be his working shift and an argument ensued because he wanted to call back when the system update (even if it means its 2:00 am and not at the convenient time that I indicated. When I explained the reason for the request, he hung up on me. As I write this review, I have not received the call back nor the airtime or data.