Yes there have gone national. The best suggestion I can make at this moment would be to go in to the Tesco, Adsa, Morrison etc, and look up the sweet aisle?
Its a good chance you might see 4 packs in stock? This is what happened a few weeks ago with me, I have to get them in the 4 pack from David sands but there were at least on offer for £1
I have been to Waitrose, W H Smith, Sainsbury, Tesco, Asda, Morrisons, Wilkinsons and a few 'small' shops but no one has them - either in singles or 4 packs. Not only that - but no one has heard of them!