Legally, I believe you aren't allowed to sell on your ticket at a profit (unless you're a well known firm that routinely buys blocks of tickets for concerts, etc., and sells them in for enormous profits). It's more a case of T&Cs causing the problem - this is nothing new it has been a standard for years. For example, It used to apply to train tickets (maybe it still does?) but no family has ever been turfed off a train or fined because dad bought the tickets for all of them, or if one person queued up and bought two tickets, one for a friend who was queueing for the buffet.And, legally, you aren't allowed to pass your ticket around! A blind eye has been turned for many a year but it doesn't change the legality as far as I'm aware.
Your letter to PB should be good. 'Dear Mr Barber, why are the club doing their damndest to stop me breaking the law?'
It was quite simply never enforced, nobody was ever bothered about it, and no harm was done. Until recently, that was the same at football matches - this new obsession for charging people to use a ticket that's already been paid for, and making it more and more difficult to beg, steal, borrow or buy a ticket to watch a game of football is nothing more than a power trip (with an element of a small (in football club turnover terms) money grab.
It doesn't need complaining about - it needs a campaign to stop it. Sadly, will probably never happen.