am i exceeding daily bandwith limit or what ???

suddenly i can't access my file manager, i tried with command line ftp and cpanel filemanager all to no avail.
i am using free plan, and i thought there was no limit for bandwith usage. and i checked on my stats that i am using 15MB bandwith for today.
what am i doing wrong ???

though i still able to access my web service as a client on this site, but i can't do anything to edit it.