Porting a Number to Xfinity mobile

Hello, I am really agravanted with Xfinity Mobile customer service. I am trying to Port in another line to get the offer of $200 back on a device or a Gift card . Now I am trying to port in the number and is says that they have a error on there side . I call Xfinity mobile and went to a store and they say that Mint mobile have a lock on the number. I call Mint mobile and they tell me that they are a prepay company and they don't lock any phone to there carrier and Gave me the account number and Pin to port my number to Xfinity. I said you know something let me try with another carrier to see if my Phone number is lock as Xfinity said.  I check with TMobile and Verizon and they say " Good news your phone number can be transferred. This clearly explain that my phone number is not lock as Xfinity mobile representative says all the time. I call 3 more times with Xfinity and they keep saying the same thing. This is a Glitch on Xfinity system and no one want to assist.