I have a contract for data bundles and anytime minutes with them yet it Dec they only loaded a quarter of my data bundle and when I queried it on the same day they load my bundle they said I used it all hence I was left with only a quarter

I have a contract for data bundles and anytime minutes with them yet it Dec they only loaded a quarter of my data bundle and when I queried it on the same day they load my bundle they said I used it all hence I was left with only a quarter. Mind you I only use my data bundle when I am not at work and not at home because I have WiFi at work and home.