Could anyone please confirm whether or not Joomla is supported by BT? I have been advised to upgrade to the Advanced Hosting Package but BT helpdesk today told me that Joomla is not supported!!!!
It would depend on how you define 'support'.
The servers should support it, i.e it should run on BT's servers.
BT will not provide technical support for it, meaning don't ask them for help if you are having problems setting it up or using it because you will not get it.