T-mobile cellular passed me back and forth between support and stores, lack of customer service, nothing fixed Internet

I have had nothing but problems with my T-mobile Samsung phone since I changed over my service to another company. I have gone out of my way to call or travel to speak to representatives about my problem and they keep swapping me back and forth between the store employees and customer service representatives on the phone to no avail. All I've been asking them to do is flash/jailbreak or unlock my phone so I may delete the old APN. They have even given me the samsung factory reset/unlock code and it doesn't work the way they said it would. I'm to the point of taking my phone back to a T-mobile store and asking them to trade me an equal phone in place of mine(which will never happen)or throwing it down on the counter and walk off and file a lawsuit, I don't know what else to do, I'm done being a yoyo!!! The only thing they haven't done is try to pawn me off on samsung, which isn't going to work because one of the store reps told me it was a T-mobile problem not samsung.