extra GB

[#1]

I understand it is possible to purchase an extra 1GB for 75P a month.
Currently on 1GB (nearly used). How do I do this.
Thank you

[#2]

Hi there,
You should be able to add more usage by following this link:
https://portal.plus.net/upgrade_process.html?do_quick_pick=1

[#3]

sorry this does not cover what I want unless I have misunderstood something. I do not want to change my current broadband package, the link you directed me to gives me this option but what I want to do is purchase 1GB.
Your main page says"extra usage is 75p per GB if you add it up front", so the question is how do I add this 1GB as my current limit of 1GB has nearly reached its limit.
Thank you

[#4]

Sorry, that link is perhaps a little misleading.
This one should do it for you : https://portal.plus.net/products/upgrade/change_data_transfer.html