Card pack issues

i also have the same problem with Toxic Citron, Breakfast Brainz, and Captain Squawk, any solution?

I switched to that pack as well, and received one character piece after another 900k. At this rate plants vs zombies 3 will be out before I get a character. 

I suspect the long delay in opening Sticker Packs is due to server load- if you watch when you purchase a pack the animation will start but it can take several seconds for the PvZ coins to be deducted from your total but once they do the pack finishes opening. For me this indicates that there was server delay in acknowledging which Sticker pack has been purchased and returning what was in that particular pack to your system so that it can be displayed.

The delay could be caused by any number of things from lack of available server resources to some sort of communication bottleneck to an inefficiency in whatever routine looks up the content of your Sticker Pack but there isn't anything that can be done at the Player level.

As far as being awarded random character pieces is concerned what your observing is the hardwired uncertainty of a random probability reward system which literally has thousands of things to choose from it's catalog. With some character pieces, like "Super Rare" and "Legendary" it probability that you'll get a piece is low so you are guaranteed to open more packs which don't give you a character sticker than you will open packs which do, and the kicker in this sort of system is that whether or not the pack you just opened had or didn't have a character sticker has absolutely no effect on the content of the next pack you open so it's entirely possible to have a "lucky" streak which you get a lot of character pieces quickly or an "unlucky" streak where you buy pack after pack and get no character pieces at all.

Because of the way the random system works you'll want to concentrate on buying either packs which specifically state that they have a high chance of a character piece or that guarantee a character piece or the unlocking of an entire character.

Once you've filled out your roster of the default character variants you'll need to focus on buying the DLC related packs to obtain the characters launched with that content and start grinding Infinity Time if the Party variant characters are desired.