I am tired of being disturbed by "your data has been depleted" messages at night.

For some time now, I am being disturbed by "your data has been depleted" messages at night. Every week, Vodacom sends me these messages at midnight, two o'clock in the morning and at four. These messages are really disturbing and in most cases I am unable to sleep after waking up. Let me make it clear, at that time, I am sleeping and I do not want to be disturbed because I am going to work the following day. So please, do not send me those messages at night. Do not tell me to switch off my cellphone when I sleep because I cannot. I have family members across the country, they must be able to get hold of me in case of emergency. Just sort out your system to stop sending these messages at night.