Im extremely upset with Xfinity mobile

Xfinity mobile was initially charging me $109.47 for services I NEVER received. I never used xfinity mobile and told them I have no interest in that service. They initially sent me an email on 08/10 that I owe 109.47 and the next day on August 11 they sent me an email I owe 333.50. How did this bill (for a service I never used) go up by this much in ONE day? They said it will be sent to collections if I don’t pay, I have a credit score of 800. I’m super frustrated because I have been a loyal customer of xfinity internet for 4 years and this is the second time xfinity mobile does this when I do not even use the service! I never inserted the chip into my phone and they have proof of that. I then spoke to customer service via chat on August 11 and the customer service representative, Nikisha, guaranteed all of the charges will be removed. Well it’s a week later and the charges are still there. I have screenshots and proof of all this.