We are sorry to hear that you are experiencing difficulties. You can also log in Xfinity xFi by using the following link: http://xfinity.com/myxFi
Also, be sure that you have a Wireless Gateway that is compatible with the xFi App. The following link will let you see a list of the compatible Wireless Gateways: https://www.xfinity.com/support/articles/broadband-gateways-userguides
We hope this helps. If it does not help, please let us know.
You might find some clues by looking at your Account.