Incompetent and infuriating Customer (Dis)Service

I recently traded in my old iPhone for a new edition at a local XFinity store. Instead of transferring service to the new phone, the store rep added an additional line. Straightening out billing errors is aggravating enough, but the CS reps insist on spending more time giving the customer a hard sell on additional products and services than helping with the accounting discrepancies. $300 toward an Apple Watch, but it's $10/mo for cellular service I don't need. Had to tell the [Edited: "Inflammatory"] four times, "I'M NOT INTERESTED, JUST FIX MY BILL!!!" Why would I add an additional product line when they can't manage the ones I already have? STOP HARASSING YOUR CUSTOMERS WITH THE UPSELLING!!!