Unusual Data Comsumption

For at least the second time this month i am experiencing unusual data consumption. My data was used up while i was sleeping. I do not have any subscriptions & i have disabled the ‘Background App Refresh’ option on all my apps The first time i notified Telkom about my problem the consultant simply told me there was nothing he could do & hung up me. The second consultant said that i should select the ‘Low Date Mode’ on my Mobile Data Options tab & promised me that i would not experience the issue again. This morning when i woke up I discovered that both my Night Surfer data and Anytime Data had been used up while i was not using my phone. I want answers from Telkom and i want my data reimbursed.