You would like to upgrade to a pack, a family or add a new style to a previous purchase. You followed the instruction as explained in the ‘Buying fonts’ section but are still unsuccessfull.
Compare the ‘Licensing information’ fields with the one found on your previous order's invoice, be sure they match. Try again, if it still doesn't work, send us the copy of your previous invoice, with a short text that explains the problem, and the fonts you would like to buy.