Sorry about the problems you're having, @Bairdy . Please try this:
- delete the Fitbit app from your iPhone
- turn Bluetooth off on your phone
- restart your Alta HR. Instructions are here. Do it two or three times
- go into a room that has no other Bluetooth devices
- reinstall the Fitbit app on your iPhone, and set up the Altra HR again
That should do it. If not, please write back, letting us know which IOS version is on your phone.