If you're a platinum member you've already paid for the privilege of being able to buy a ticket for £25. Therefore you can't buy a ticket for £25.
And if the club has seriously advertised the prices in this way in order to allow away fans to buy tickets at a lower price than that available to...
And for the avoidance of doubt, the club's webpage announcing the new prices states
This means fans can get a ticket for as little as £25
which is quite plainly untrue.
ASA clamps down on misleading ticket prices27 February 2013
The Advertising Standards Authority (ASA) today ruled against four theatre ticket providers for quoting misleading ticket prices on their websites.
We found that compulsory fees and charges were not being included up-front in ticket...