Unfortunately, we are not allowed to represent individuals ourselves or provide legal advice, and we cannot make specific referrals. What I can tell you is that if you do not make much money, then you may qualify for assistance through your local legal aid office. They provide free legal representation to low income individuals, and cases involving children are high on the priority list. Among the services offered are modifications of custody decrees, and as said above the child's preference is a factor the court will consider.
Another factor the court may consider is a parent's leaving the child with a non parent on a regular basis. That too, in fact, might be deemed a violation of the order, because most plans state that the child is supposed to be with a parent during those times (except when the parent is working). And of course any form of verbal or emotional abuse would be unacceptable. Depending on the severity, might even result in a suspension of visitation
If you are not able to get assistance through legal aid, you can always retain an attorney for limited representation - meaning, advice and assisting with the drafting of the paperwork. As for the cost involved, $3500 might be a good estimate for full representation, based upon the information you have provided, but ultimately what an attorney charges for full or limited representation varies considerably on the attorney, his or her caseload, skill and experience, and the particulars of the case. Lastly, if you must pursue a matter like this on your own, you can contact the clerk of court (some courts have forms or a self help desk available).