Father can ask, but if father is moving further away from you than he is now then that's the father's problem. If you had moved with the child further away from father than you are now then he'd have much better grounds to complain.
The order is the order until the order is changed. So yes, the order is a legally binding document.
When he says "I'll take you to court" he's trying to scare you or bully you. He's free to take you to court to change the order at any time for any reason. It's up to the judge if he should get what he's asking for. But he's entitled to ask any time and it's no threat to say that he will. That would be like me threatening you with how I'm going to vote in the next election. Or me threatening you that I'm going to take you to court for custody of your child; I could certainly try and there's nothing stopping me from trying. Well, I don't know who you are but if I did then I could try if I wanted to.
If the support is registered with your provincial support enforcement agency, they'll keep after him for the money and keep track of the arrears. After a while, they'll start garnishing his income sources, tax refunds, take away his drivers license, and eventually take him to court.
If he's ordered to provide you with his income tax returns or notices of assessment and he's not, you can take him to court for finding that he's in contempt of the order. I'm sure he's earning more than he was in 2012. That's usually why the payor won't disclose the income. Either that or they haven't filed income tax returns because they don't want the support recipient to get the tax refund, or because they are too lazy or disorganized to file.
Anything else about this topic you'd like to discuss?