Complain

I am writing to complain about an employee at the Xfinity store on Lincoln Avenue in Chicago.
I recently visited the store to exchange my modem. I was told that the store employee could activate the replacement modem and test it to make sure everything was working properly. However, when I asked for assistance, the employee flatly refused and simply told me that she could not do it. She made no apparent effort to assist me or find another way to resolve the issue.
Unfortunately, this is not an isolated incident. This is the second time I have had a very negative experience with this particular employee.
The previous time I visited this store, I was there to pick up a new modem after ordering my service online. The employee refused to give me the modem because I did not want to activate a mobile line. I ultimately had to go to a different Xfinity store just to pick up the modem.
What concerns me most is the employee's consistently unhelpful attitude. Her responses to customers seem to be "no" rather than an attempt to provide assistance or find a solution. On both occasions, I felt that she had no interest in helping me as a customer.
I understand that there may be certain things store employees are unable to do, but I expect them to explain the situation, offer alternatives, or direct customers to someone who can help. Simply refusing to assist a customer is not acceptable customer service, particularly when it has happened to me repeatedly.
I would appreciate it if this complaint could be formally documented and reviewed by the appropriate store manager or customer service representative. I would also like to know what steps will be taken to address this issue, as I should not have to visit another Xfinity location to receive basic assistance.
Thank you for taking the time to review this.