New iphone with battery message

I just bought Iphone11 about 2 weeks ago and within a week and half I got this message :Unable to verify this iPhone has a genuine Apple battery. Health information not available for this battery. The battery does charge for hours on end the phone turns on and off all the time. Took it to Telstra shop (where I bought it from) they reckon never seen it, restarted it went back to normal then few days later the message is back the phone does not charge. Apparently I am was being rude for asking questions about the faulty product I was sold. So disappointed might take the complain to consumer products complaint. Still paying for the plan and the product that doesn't work properly.