Brand new apple watch series 9 watchOS 10.5 drains from 100% to 0% in matter of few hours and apple support is a joke

What a **** show Apple is. I bought a new series 9 watch worked perfect for a week (probably had 10.5 or 10.4 version) and then one day battery drained from 100% to 0% in 2hours. I rushed to apple care and they said its software issue. Anyway I returned watch as it was under return period and got a new piece of watch.

New series 9 worked fine for a week, it has 10.5 version and battery is draining 100% to 50% in 4-5 hours. Service center people says it software issue and battery is 100% good but would not say which software is causing this issue and when it would be fixed.

well my phone and I phone are updated to most recent OS still this issue is there. What apple wants us to do? Charge watch 4 times a day?