High local usage

I have inherited a site that was set up , it is all up to date using 3.6.1 with all plugins and themes up to date also , the allowance per month off our current host is 1.5 Tb which we are using at an alarming rate , we average 10,000 visitors a day on the site alone and the forum (the forum is phpBB) and doesn’t have any issue’s that I can see , the amount of local usage is constantly rising and i have contacted the hosts who gave the following reasons , can someone point me in the right direction please here are there comments ,

Me:- As our host’s can you please forward a breakdown of our usage as this is by no means normal traffic , were is all the usage going as there is nothing to download off our site , as its a read and post a comment only blog and forum , seem’s strange to me that we are getting once again to many connections when all connections go via your server and our own site stats say we are averaging 10,000 visits a day , hardly what i call an upsurge is it ??? thank you in advance .
Reply :- Please note that blogs can actually generate a lot of traffic (especially local), because your website scripts are constantly accessing the database and downloading different content, which after that is downloaded and seen by the site visitors. If you look at the traffic statistics page: (removed link)
you will notice that a lot of the traffic is exactly local. And when we add the web traffic generated by the site visitors we get the total traffic for your account.
Me:- “a lot of traffic (especially local)”, well what do you suggest in order to reduce this as the local usage is more than the out going , which unless you can tell us exactly why this is or what the cause is ie:- a faulty plugin or whatever the explanation is of little use is it ? , thank you
Reply:- We can see the queries to the database from your website, but there is no way for us to determine which script is running then, and whether they are supposed to be this way. You can speak with your website developer about optimization if your website in order to reduce the queries as whole, but frankly I am so sure if the developer will be able to do something to make a difference simply because your site is being accessed a lot by visitors.

I think he meant to say “frankly I am *not* so sure” , any help would be appreciated , thanks for your time and any replies .