Error Message Assistance Needed!

Hello! I need assistance with an error message I am getting when trying to use the secure message center through my Barclay credit card website. The website itself works perfectly, however when I click to view messages in the message center it comes up with an error message that reads, "The requested URL was rejected. Please consult with your adminstrator. Your support ID is: (16 digit number)." I have tried to access the site from 2 Macs running safari, a PC running IE, an iOS phone, and an Android phone and get the same message on all devices.

Can anyone help? Is this an issue on my end or on Barclay's end? Their tech support has been absolutely dreadful and I am trying to avoid calling them again...

Thanks in advance!!!