MTN Data

I have a router contract with MTN. In January after they loaded data it got depleted in 2 days. I received a statement that showed that the was activities on days that there was no data in the router. Now in February the data did not even last for 10 day. I need to understand and get a clear statement that shows what the data was used for. There is no way that 100 GB can be depleted in 10 days. If there is anything they must cancel this contract and I will find a better service provider that will not reap me off.