Fibre extra vs Fibre unlimited products

[#1]

I am a fibre extra customer and have read on this site that the priority given to my connection is not quite as good as fibre unlimited. Assuming the only way to get the best priority is to upgrade to unlimited I assume this would mean taking out another contract?    
Is this a case of preferring new customers only or can existing ones be given the same priority or upgraded to a pro connection for gratis to encourage renewal rather than leaving me to start shopping around?!
https://portal.plus.net/support/broadband/speed_guide/broadband_experience.shtml

[#2]

Isnt Extra a old plusnet package and extra = unlimited package, whereas value was a old package and the new one is now essentials.

[#3]

Thanks for your reply. I just realised that it does look like they are treated the same now, I must have been looking at an old link!

[#4]

The legacy Plusnet Extra Fibre has a 250GB per month allowance with P2P, Usenet and external FTP rate limited to 2Mbps from 8 to 10pm. The current Plusnet Unlimited Fibre product allows unlimited usage without any rate limits.
The cost of Extra Fibre and Unlimited Fibre is identical on Market 2 and 3 exchanges, Unlimited is 50p dearer on a Market 1 exchange.
As far as I'm aware upgrading from Extra Fibre to Unlimited Fibre involves starting a new 18 month contract; however I suggest ringing the Customer Options Team on 0800 432 0200 or 0345 140 0200 (Monday to Friday 0900 to 1730) to see if they can offer different arrangements.