MTN Mobile data not reflecting on device

Good morning, I need assistance with the data contract on my tablet. Called 135, but that system is not user friendly. A lady called to offer me an upgrade on my contract on . The upgrade was done in August and I see that this was successful as the latest debit order has changed. However, Mobile data no longer reflects on my tablet. I noticed this the day before yesterday when I wasn’t connected to WiFi. Please explain what is going on. Thanks