This is a Roku Tv? The remote would have to be wifi for it to reach and control your tv from the neighbors place. A wifi remote can only be paired to one device at a time, either yours or his, can't be both. Did this happen more then once? He could have paired to your roku while attempting to pair it to his, while it was controlling your's it wasn't controlling his, so I assume he continued programming it until it did control his. And so you shouldn't have anymore conflicts until one of you starts programming again.
If the above wasn't the case, and your tv uses IR, is there a IR repeater device in your house so can control devices from another room? Many RF to IR system interfere with each other, only remedy is one of you to abandon it.
Speak with the neighbor find out what's going on?
Edmund
