How do I get the 3 year warranty for my Elite Series 2 Controller

They recently extended the warranty for elite 2 to one year. https://support.xbox.com/en-US/help/hardware-network/controller/elite-controller-series-2-warranty . maybe this will help

I bought Xbox Wireless Elite Series 2 Controller, Here in EU (Greece) all controllers have 1 year warranty and the Series X/S consoles 2 years.

You can get Microsoft Complete within 45 days of device purchase by contacting one of our support service agents Contact us | Xbox Support.

If you experience any issues requesting a call back or live chat on the Xbox support website, go through Microsoft support. Once you get to the virtual agent just say “Talk to an agent” and select Xbox as the product, and your issue from the list. Select the option “Call me back” or “Live chat”, which shows the estimated wait time/queue.

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My elite series 2 rb button doesnt work and i cant find a replacement button how do i fix this

Microsoft knew the controllers were defective and still sold them as a good product. they wont do anything to fix your controller because its most like out of warranty thats why the warranty was so short. The whole elite series 2 was a scam

https://answers.microsoft.com/en-us/xbox/forum/all/defective-xbox-series-2-elite-controller-and-class/2b11a3b7-d094-4073-97b7-da1dafba71ce

It definitely should have been a year. From late 2020:

"To ensure your satisfaction, we’re extending the warranty coverage period on Elite Series 2 controllers from 90 days to 1 year from the date of purchase."

https://support.xbox.com/en-GB/help/hardware-network/controller/elite-controller-series-2-warranty

That still applies far as I know.