Negative experience with buying a new phone

My last experience visiting Xfinity office was extremely negative. I'm elderly person and got confused with choosing iPhone. I wanted to replace the old device with a new one and keep the old phone number. Instead, the person who served me added the phone that I refused, add a new phone number and additional line to my account. I still have not received a refund for phone I refused. Also I received a very large bill for using two lines and two phones, while I use only one phone and one line. I see, that Xfinity priority is to get as much money as possible from customers and not the interests of customers and satisfying their needs. I'm seriously thinking now about changing mobile carrier (provider).