How to get refund for accidental on demand purchase

If an employee doesn't help you here in the Forums you'll have to keep trying to contact one of their Billing reps and ask them to issue a credit. Call them at the phone number on your bill or 1-800-Comcast, use one of the options on https://www.xfinity.com/support/contact-us, or visit a Service Center or Xfinity Store if one is nearby (check locations and hours at https://www.xfinity.com/support/service-center-locations/).

In addition to getting the billing corrected, consider setting up a Purchase Pin on each of your cable boxes/DVRs and in the Stream app and web portal to prevent this from happening in the future. See https://www.xfinity.com/support/articles/parental-controls-non-x1 and/or https://www.xfinity.com/support/articles/x1-parental-controls-turn-puchase-protection-on-off and/or https://www.xfinity.com/support/articles/x1-manage-tv-settings-online.