The number to ring to activate an FSFS Card is provided on a letter accompanying the Card. Don't call any other number.
As you can see, the Terms & Conditions are very clear and they cannot charge you a further fee because you do not choose to provide a phoneline.
That £25 fee is, however, applicable to folk taking a non-multiroom Subscription and electing not to fulfil the 12 mth connection requirement that would otherwise apply.
Whoever you spoke to is not adequately trained and has mixed up two separate issues.
Finally, the "Interactive Features" referred to in what you posted are NOT the Red Button stuff that you might at first think, but all the Sky crap that has nothing to do with watching telly and everything to do with emptying your wallet. I feel sure you do not wish to access the Interactive Services referred to ...................