I got the Lebara sim from India before coming in ...

I got the Lebara sim from India before coming in to UK. It's just 4 days and I have already lost over 30 pounds. Not sure how the company bills. Within no time, I get an alert that my balance has gone below 2 GBP. Just sceptical to use this sim. I wish someone from Lebara reads this and explains and compensates.