We've gotten the soda package multiple times. All good. There is a machine on the promenade and in the Windjammer. You need to use the soda cup they give you for refills. There is a chip in the bottom that activates the machine. Otherwise it wont work. If you don't like the taste dump and try something else.
Also, on your seapass card it will indicate soda package. You can show your seapass card at any bar for free soda.