If you contracted before Feb 2013 you would be on Unlimited broadband. This means you have unlimited data upload and download limits. It does not mean that your connection will not be limited at peak times.
If you contracted after Feb 2013 you should be on Totally Unlimited. This means you have unlimited data uploads and download and you will not be limited at peak times.
If you re-contracted after Feb 2013 you may not have been automatically put onto Totally Unlimited unless you asked for it when you re-contracted.
If you have not re-contracted and are on a rolling monthly contract you will be on what ever package you were last contracted on.
Telephone the Options Team on 0800 800 030 and ask them what package you are on and if need be you may need to re-contract to put you on Totally Unlimited. If you have any problems post back here for further advice.