Hi guys, need some input:

My place of work uses a Vigor 2820n with Be internet, whom have recently changed their DNS servers, meaning that internet access has been somewhat erratic. The issue is that I am only a recent addition to the workforce, and I don't know what the username and password are for the Be account, so I can't just reset the router and use the new settings.

How can I update the existing configuration to use Be's new DNS settings without doing a reset?

Be do not use user names and passwords for their connections.
You should just be able to log in to the router and change the settings for DNS to whatever you want - I would change to opendns servers rather than sticking with Be's though.

I've been into router config, but it's totally different from anything I've seen before (I'm used to Netgear, you see!) Where would I need to look to change the settings?

Go to WAN > Internet Access
Select the WAN1 link on the next screen.

At the right hand side should be the addresses of the DNS servers

Many thanks!