They responded and ours works with our 7 Plus's! Here is the response;
Please try to follow the steps to clear previous error and pair again from the beginning:
1. Clear (forget) connected tune2air from iPhone after the phone has connected with tune2air, then turn off the Bluetooth of the phone.
2. Restart the iPhone; pls don’t turn on the Bluetooth of the iPhone at this moment.
3. Unplug the tune2air and plug it, the blue light will start to blink.
4. Turn on the Bluetooth of the phone and pair it with tune2air from the beginning.
Remember! When you trying to connect to the viseeo with your phone you need to have at least one song in your ipod library.
And it's this last part that fixed it for me. I don't use iTunes, we just stream through Amazon music so we had deleted our iTunes and Apple music apps. I installed it, added one song we had in our history and it works perfectly, didn't have to do any resetting that they mentioned. I jump in, play Amazon music, I use the steering to change tracks and adjust the volume, just what we wanted. Hope it helps someone else.