MTN decide for me when I can use the talk time minutes I buy without telling me so at point of purchase

Switched to MTN recently on prepaid. I bought 120 for 30 days talk time minutes under the ' MY Town Option' on my MTN App. No where on/in this option does it say that the 120 minutes are divided into 60 daytime minutes and 60 night time minutes (I also cannot find info on the MTN app either on/at what time the MTN day/night times start or end). I now receive sms messages saying that my daytime 60 minutes are depleted and I should buy more minutes (for daytime use). So no info anywhere about how I am allowed to use the 120 minutes when I bought it. I feel cheated!