[Android Central Question]

I'm having an issue with my LG G6 using data. I've only had it a few months and I have never been able to use the mobile data on it. I connect with WiFi, but I cannot use the Internet without it, nor can I send or receive group messages or picture messages. I have contacted my network carrier (ATT) several times and even went to the ATT store and even stumped the managers on duty. The only thing they could do was offer to trade the same phone in for less than half of what it is worth. I like my phone and I don't want to get a new, but I also would like to use it and get what I paid for.

[belodion]

If it’s faulty, they must replace it; if you bought it yourself, make a manufacturer’s warranty claim.
I’m not sure that ‘stumping the managers on duty’ means that it was fully and competently tested, however, with no disrespect to those managers. What did they do before arriving at the state of being stumped? Tell us that and we may be able to narrow it down to a likely cause of the problem.

[Rukbat]

Go to the AT&T store and ask where the Device Support Center is (that's their store that does actual repairs, update flashes, etc.). Go there and see if they can fix it. (Some of them are pretty good.) I even had one phone that was way out of warranty, that was ruined by an update, replaced.