My broadband connection (reliance)says that i used about 2gb last month,but dumeter(a sofware)says 700mb?

My broadband connection (reliance)says that i used about 2gb last month,but dumeter(a sofware)says 700mb,which is right?is there any other software for me to measure downloading&uploading daily and able to give me the result at any time(in du meter i can see the down&up daily,weekly or monthly)...hope u do
Answer
If it is an open wireless network you may have poachers