How do I know the call I received was legit and I was not scammed?

[Sky19]

I was multi-tasking and answered a call from someone saying they're from Telus. I had just ordered a new phone an hour prior with Telus- I had called in. The caller offered me a better plan and a better phone. He said I need to return the 1st phone I ordered an hour ago when it arrives (I'm supposed to call him for shipping instructions) and then he can send my new phone (can't have 2 promos at the same time). His name is Mark Henderson agent number JKB3213. After I hung up I thought maybe I should've paid better attention to the phone number (403-403-5672) and maybe it's too good to be true and I am being scammed. How do I know if this is legit?

[Nighthawk]

100% scam. Fake phone number, fake name, fake employee ID. Common scam.

Do NOT call them back. Do NOT ship them anything. You'll still be on the hook for the device. It's part of how this scam works. If that scammer sent you to a webpage to put information in like an email, password, etc., then you'll need to change all of the associated passwords. If you gave them payment information, you may want to cancel the card.

[TELUS_Support]

This is correct. Everything @Nighthawk has said is accurate. 

I would also report this incident to the Canada Anti-fraud Centre. This is the form and the site will also have valuable information on next steps.