data theft

Hi,I will like to file a complaint because I purchased a whatsapp bundle on Saturday the 20th of April 2019, And in a matter of less than 24hrs of having the bundle which is 1G ,I lost 600mbs just like that and I haven't sent anything such as videos and stuff and I only sent messages people so please do tell me how is that even possible that I lost so much data this service provider is false data just vanish like that I would like for this issue to be sorted out