First, spoofing the Empower ANI is very simple for scammers, it's a no-loss proposition since the caller ID say's the call is from Empower. It helps the ruse.
Second, if you call Empower back you will get Empower. There's no way they hacked the switchboard to route your call back to them. Your phone shows Empowers number because that's what number they told your phone it was coming from. It's why the number matches what's on Empower's website.
Third, be sure to talk to someone from the fraud area at Empower. They will want to know.
The only reason I know how this goes is that someone attempted to pull the exact same style scam on me (refunding money through Zelle, lol), and I kept them on long enough to catch a flaw in their script. They expected me to have a savings account, which I don't, so it became obvious they weren't from the customer service area because they didn't have access to view my accounts. They called me early in the morning, so it took me a bit to wake up and catch on, but once I did, I hung up, called my bank, and specifically talked to the fraud department to both ensure I didn't lose any money, and that Zelle was prevented from being connected to my account.