getting 403 this action is unauthorised when trying to log in to website

Hi,

I can no longer log in to a website that I access for work everyday .

Across all of my devices when I attempt to log in I receive a message that says 403 | this action is unauthorised.

I have contacted the company and they are not aware of any issues on their end and advised that I clear history, switch off and on device both of which I have done but after doing so I still cannot log in. I have also switched off wifi and reconnected and turned my router on and off to no avail.

Any ideas what I can do next and is it likely to be a problem on my end or the websites?

Thanks.