Telkom missing data

I get my 40GB contract data on my router on the 1st of every month, but on the 10th it gets depleted but I use it only on my phone and I work during the day. I even changed my router password thinking someone has excess, but it is the same thing every month. I called and asked for a report showing where my data goes to because it is not on my phone as I use less than 5GB on my portable router for the rest of the month, know one helped me- they said they dont have that information. This really makes me angry because now it feels like I am getting 1GB instead of 40GB.