I can confirm you can still buy Wagon Wheels in most places (in fact you're most likely to find them in Poundland/Poundstretchers), but they are shadows of their former selves. As someone mentioned I think they took out all the "yummy" additives as the consistency and taste isn't as epic, and moreover, they're SO TINY nowadays.
And no, it's not "you got bigger, they stayed the same", they're genuinely WAY smaller!