The way these happen is: · The service (Amazon etc.) tells you to go to a URL and enter a code.  When they do this, they expect you to do exactly that. However, quite a few people don't.  There are many ways to go wrong on this, including: · Type the URL incorrectly.  Just look at the way there are 50+ ways to spell Roku on a Roku forum - mis-typing is easy. Or: · Enter the URL into a search field instead of a URL field.  (Some people don't know the difference, some people do but occasionally goof.) Or: · As you are typing, your browser is set to offer search suggestions, and you click on one of those instead of continuing to type. · Then, once you get there, you don't look at the URL field to make sure that it actually points to a domain for the service that you are trying to link to. · Once at one of these fake sites, they tell you you have to call so they can size you up and see how much they can get out of you.  These sites are often Advertised sites (ie: they pay to be ranked highly) - especially if google is your search engine of choice. (Bing was MUCH "cleaner" last time I checked.)

You can modify your Roku account at https://my.roku.com to require a PIN to add channels and only add the Amazon channel to the device, removing all the others. They could still see the channel store, but couldn't add any new channels without your four-digit code. Note, all devices on one account share the same channel list, so you'd need a Roku account specific to this use base.