Data dissapeared

I had about 40gig nite data left on my mobile. I tried to access it during the night but it would let me. I called the callcentre where I was told that I should have called in the middle of the night. I mean who makes calls unless its urgent during the middle of the night. I thought its a call centre so they have my details on the system. Really how can i just lost so much data its not my fault. Please give my data back.