Safari will not open Barclaycard login site

to be honest boss, i don't know why this is, but i would provide more information than just that, saying that it could be a firewall issue or a anti-virus issue, try changing some setting there.

What specifically happens when you try to log in using Safari?

Try disabling all of your Safari extensions. Go to Safari's preferences window, click the Extensions icon and toggle the big On/Off switch in the upper right corner of the window to Off. Then try logging in again. What is the result? If you can log in, one of your Safari extensions is causing the problem.

i have the same issue on many websites, i.e., i can log-in with firefox, but not with safari (8.0.6; OS 10.10.3)