Airtel — internet stops working from 1am at night

Internet stops working from 1am at night.. And next day again in works from morning. Whole night it doesn't work. I am very irritated of this. My scheme is for 70 days daily 1gb. Whole day i use only 400mb, nevertheless it happens daily. Everyday after 1am it stops working. Even simple message also doesn't go. If it will happen regularly, i will change my sim to other network company.