Xfinity Home Indoor Camera

I have XFINITY Home and recently my touchscreen got upgraded with the newest one.  This meant that my 3 older cameras no longer work and only 1 works which is the latest Indoor Camera.  I was trying to purchase another Indoor Camera through Xfinity's Website but it kept failing, do I need to go to the store to order the new camera?

In addition, what is the Model Number of the latest Indoor/Outdoor Camera, is it SCHX4AEW?  I am looking to purchase a used one but I wanted to make sure that I order the correct one.