Excessive Data usage on router.

Hello.

This problem is sending me insane. I am on holiday in Turkey, I come here regularly, I have with me my TP-Link Router. I load it up with the maximum internet package from TurkCell. 20GB at a time. On Average I burn through around 1GB each day, thats ok, no problem Over the last two days I have burnt through 10GB. The same thing happened with my last internet package over two days 10GB gone. I don't stream films or sport or TV programmes I use it for email a bit of google and FB contacts. I went into the local Turkcell shop, they told me it would be correct and I have used all the GB on those dates. They couldn't tell me on what it was used only that I had used it on those dates. My WiFi is secure and nobody else is on my network. Can Anyone out there save my sanity and tell me if there is anyway my Mac can tell me where that usage is going. It's happening as I write, my router information page is clocking up 1.7GB.....1.8GB.....1.9GB....2.0GB. I've lost the will to live.....Thanks for listening.

Keith