With coins you can buy special treatment points. Why not visa versa? Or buy coins/special treatments with club money?

For 46 coins you can buy 50 special treatments. Why not trade 50 ST into 46 coins?

My club has a lot of money in the bank 5B. I cannot use it (only bid high on players but need also coins for it).
Why not buy special treatments or coins with money? Like real live....