I reported this to ZOS on the 5th after the maintenance, 5 days ago now and was told I would get a response from an escalation team. I was also advised not to spend the crowns. As of yet nothing.

I don't know how this happened. I also noticed in the Account area it says I joined PTS the same day, however I personally didn't do anything in that regard. I've never engaged with PTS so I'm not sure if that's related of if you just get auto-enrolled at some point.

When I purchased the game I had issues with my first Crowns and pack items not being delivered - apparently there is a known issue by ZOS that purchasing Crowns at the same time as the game can cause them not to be delivered. To that, ZOS owed me something like 29.5k Crowns and it was fixed by support. From then on I've had no issues with delivery of purchases. I've since made Crown purchases - however not in the last few weeks and my ESO+ doesn't renew until July.

Either way, I'm a bit perplexed at how I've ended up with 26,000 Crowns I didn't pay for. I wish I could know what's going on because I don't want to engage with the crown store at all or buy crowns until I know my account is safe.