Can accidental purchases be reversed?

You can go through the in game help menu and contact EA Help, there is no guarantee, but it is worth a try.

Tried that. I'm not sure the EA rep knew exactly what was going on. I tried to explain it in as much detail as I possibly could. But he ultimately said they had no way of reversing it from their end. And to top it all off he directed me to the play store after that. Once that happened, I knew he had no idea what was going on. Does anyone know if there is anyone else I can try to contact about this?

Had exactly the same problem (isn't it crazy how pockets take the freedom of purchasing packs on your behalf?)
Tried to ping-pong my way through 5 or 6 customer support help (most of them had no clue what they were talking about), and the last one said "nope, there is a policy of no refund for crystal purchase".

One passed (according to her) the message to devs to make it a little less easy for the app to do that (e g. add a confirmation screen).
Apparently the devs got the message and did the exact opposite: when a pack goes live, you have now a one-click purchase directly from the home screen. Go pockets (and kids etc.)!

So short answer: enjoy your shard shop token!

Fun stuff. Thank you for responding!

Fun stuff. Thank you for responding!