Anytime broadband

[#1]

Hello, This may seem like a bit of a naïve question. I have just signed to Unlimited Broadband with Plus. Net. However on my billing screen, although it says unlimited, there is a screen which monitors my usage with a ribbon progressing towards a somewhat small limit of 500MB. I wondered why this is - I assume all my broadband usage is without charge. can someone clarify please? 

[#2]

It automatically scales to your current level of usage. You'll see the upper limit increase as you use more.

[#3]

It's a legacy feature.
The bar scale is recalibrated when you reach the three quarter mark or similar
There are a few customers on legacy products who need it others like the info  

[#4]

Thanks for your prompt replies. That's set my mind at rest. Cheers.