Hmm.
A bit of guesswork here. Although Snack-in-the-Box is a completely separate company to Cadbury, they only sell Cadbury products and have acquired the right to use the Cadbury brand (
and associated logos) on their boxes.
I'm wondering if, when those boxes were new, Cadbury (rather than Snack-in-the-Box) was participating in raising funds for the NSPCC. (i.e. you'd have seen the NSPCC logo alongside Cadbury products in your local shop, as well as on the boxes). In which case, old boxes might still be in use, even though the fund-raising ended some time ago. (Cadbury is currently linked with World Aids Day but not, as far as I can see, with any children's charity).
Alternatively, since Snack-in-the-Box is a franchise operation, the guy who delivers your stock is running a completely separate business to any other franchise holder. Maybe he alone is raising funds for the NSPCC. In which case (unless he's entered into a formal arrangement with the charity) he's free to decide what percentage of his profits he donates to charity.
Speak to the guy who delivers the boxes or, if you're concerned that purchasers might be being misled, choose a suitable contact here:
http://www.nspcc.org.uk/whatwedo/aboutthenspcc /Contactus/Contactus_wda33279.html
Chris