Look man you seem like a good young guy. Hey, I don't know if you did the work to standards or not or even if you completed the job according to the contract details. But for the sake of argument lets say that you did everything that you were told to do and you followed all the guidelines, communicated well and invoiced truthfully.
You got a couple options. Real life options and not this pie in the sky "go hire an attorney" BS. Attorneys only make money for themselves and you wont get but a fraction if anything by the time its said and done. And it wont be worth your time and energy. Its better to move forward and get on with things. Dont listen to these other peckerwoods on here that just like to hear themselves talk. Old guys and young guys alike. These folks have too much time on their hands. I just happened across your post in passing, I dont spend much time on here.
The first option is to stick it out with these folks that you are contracted with and why not, you are already there on site, contract is in place, insurance is paid for. Communicate with them "without emotion" like spok on startrek. Dont get mad or pissed off, thats too easy and its only going to make matters worse. After all you want to get paid dont you. Would you want to pay someone that was being and Arsehole? No, just keep your cool and do everything that they ask you to do. Show them that you are willing to go the extra mile to rectify any outstanding issues. Have a communication trail via email. this is so that the words that they type will hold them accountable. And above all talk to them in person when all possible.
Look man keep this in mind. The way that God designed the universe is like this, if you do what is right regardless of how much it hurts, then you will be rewarded in the end and the people that wronged you will suffer. This is only true IF you maintain truth (dont lie, dont cheat and dont steal). So while it seems that you wont succeed, thats just your limited thought process, you will in the end. God keeps score and because of this you dont have to worry about it. Just do what is right, be truthful and youll be taken care of.
Your second option is to plain and simply "move on". But only if youve exhausted option one. Now the lesson here is to not get into this situation again. You see being in business is all about relationship building. You have to know who to trust and who not to trust. Peaceful as a dove and shrewd as a snake. Never enter into an agreement to do work out of desperation, men of good standing dont act desperate. They let their quality of work speak for themselves and because of such they demand good pay and steady work. If you are a liar and a hustler then you will never succeed. The laws of the universe will always be against you. And though you think you are making good money, you never be able to spend it, instead it will be like trying to hold water in your hand. Or it will fly away like an eagle and youll never get it back.
Look man, this cable tv industry has reached peak bullsh!t.
Its turned that way because of all the hucksters and liars, backstabbers, punks and cheats. You can still make money though, but its going to be tough. You are really going to have live in the trenches until you build up a reputation for yourself. Once you have a good reputation then you will be able to pick and choose and work for the people that you want to work for and not out of desperation.
Do what is right
Remember that when people think that you are desperate then they are more likely to take advantage of you.