What to do about swollen battery on Apple Watch Series 7?

Battery swollen and pushed face completely out. Series 7, only 3 years old and not worn very often at all and always kept with charge in it. Apple told me over the phone that they would repair and would give me a call the following day. Called me back, hung up on me and now I’m getting the run around. The battery is dangerous. Could have caught fire, exploded, who knows. They need to take responsibility for this.

[Re-Titled by Moderator]