Hi davedachef,
If in the the upgrades and offers section you see an Oops something went wrong message, it's because you either already have a discount and the systems require an extra bit of manipulation by the agents to set up any new discounts, or because the package you are on is no longer sold and again requires the extra manipulation by agents to change the package.
Unfortunately there's only two other ways to upgrade, text or phone. If you don't want to be tied up on the phone then you could try the text messaging service.
Just send a text with a description of regrade to 07533 051809. Your message will go into a queue and a representative will respond to you as soon as possible. It's not instant and may take a few days.
If phoning it's best to call first thing on a morning, 8am, as it's less busy then. Dial 150 from a Virgin landline, or 0345 454 1111, Options 1,1 and 4 Changes to your package
Sory I can't help with the website signing you out.
As to the forum message tags, I've had the same problem when speaking to staff in private whilst trying to order a wifi booster, the forum wouldn't allow me to type my password. I'm not sure if the people that run the forums can update the settings, I think they are probably set on a standard blacklist. I manage some online chatrooms and use their standard blacklist which is quirky to say the least, I can add words/sentences to be banned, but can't alter the preset ones unless I turn that setting off completely.
Dave
The Service you do for others is the rent you pay for your room here on Earth - Muhammad Ali