Support is dealing with a huge, huge backlog - so it’s likely snowed under. Calling them works, or giving them a little nudge if you’ve been waiting for weeks by posting your ticket number in the topic over here.
For others finding this topic - What we know on the forum at the moment:
If your phone is still in warranty, they may still have some replacement batteries available (though we’re not sure, nobody has reported back recently). If it’s out of warranty you’ll have to buy a new one, but annoyingly the next shipment of batteries isn’t expected to hit the shop until August (you can sign up to be notified when they go on sale).