Disappearing data

I had my new Lebara sim in my phone for 10 days, then at 3.41am, over 2000mb of data went in one go. Lebara told me this was normal. I don't think so! Anyine else had similar issues, or am I just lucky?

Same here, bought a new sim for the caravan wifi. Overnight when we were asleep with all devices switched off 10GB was used. Lebara support dont want to know. They just told me to check stats on my router admin page but it only lists devices currently connected. Router is password protected and has never had this issue before.