I use Castrol Valvemaster Plus in my 2000hf coupe. I was under the impression that the product has been discontinued by Castrol and have stockpiled what stocks I came across.
It now appears that both Valvemaster and Valvemaster Plus are still available but not marketed as Castrol products. I am assuming that it is the original manufacturer which is continuing supply. Their website extols their marketing prowess but my experience has been that they have been remarkably opaque and unsuccessful in advising existing users that the product was still available. I have considered the Miller equivalents but like the "Castrol" products' relatively lower cost and ease of use.
The Castrol Valvemaster Plus 250ml treats 250l of fuel at approximately £10.00; the Miller VSPe Power Plus 500ml multi shot treats 500l of fuel at approximately £30.00.
The Miller products claims to also combat the adverse effects of ethanol in unleaded petrol up to E10
https://classicvalvemaster.co.uk/where-to-buyI may give Valvemaster a call in the new year to get additional information which I will share.