Hi there @petefoxon, welcome back to our forum and thanks for your post.
If you do wish to see the last few months of data usage you can do so via your mobile online account here You can view bills up to 12 months back. If you view a full PDF copy of your bill you can see a full breakdown of the allowances you have used in that particular month.
Unfortunately there isn't a way to see the average usage on the online account, it would just be a case of adding up the months usage and dividing by however many months average you wish to see.
If you need any further help with this, please let us know, we will be happy to assist.
Regards
Nathan
