Data disaster

I bought 5gig worth R405 of data on Saturday the 25th of August. Used my phone as normal like previous months which 5gig normally lasts for about 3 to 4 weeks and to my nightmare my data was depleted by Monday evening the 27th. I then phoned to find out what happened and the lady that assisted had no clue how to assist and instead of solving my problem she looked for excuses. She ended up advising that she will refer me to her manager who will call me and till today I haven’t received a call from vodacom regarding my query. I don’t understand how 5 gig depleted in 2 days as I’ve been buying the same amount of data previous months and it lasted for more than 3 weeks .