Identity theft by employees

My credit was ran without my permission after signing up in a store in January, I received a letter saying my credit had been run by xfinity mobile and it was never approved by me. I assume their employees have bonus incentives on mobile and signed me up when I was in the store. I immediately went into the store and asked why my credit was ran and wasn't provided with an answer, and was told I did not have a mobile account with them. I cancelled my services at that time for internet, turned in my devices and asked if there were mobile items on my account and was told they did not see anything. Fast forward a few months I am now receiving collections letter for serveral hundered dollars, and when logging into my xfinity account it shows almost $700 and 5 phone lines on my account. I have asked to be provided with a signed contract with my signature showing approval of this and running my credit as it is identity theft, and a federal crime to run someone's credit without permission. I am seeking legal advice as soon as I find out the employee that ran my credit application without permission. 

Do not trust this company and its associates.