What should i do if i haven't gotten child support in over a month?

I filled for child support last December on my son's father.. I was getting it every month up until last month. The last payment received was on June 2nd.. He's had several jobs since i filled and ive never had a problem.. I talked to him last week about the child support and why i havent received anything, he told me when he started his new job at the end of may that he called the child support office and told them about his new job and that he wanted it taken out of his checks.. He told me that if it wasn't taken out on his check friday that he would go in and pay it. I called the 1-800 number this morning and its saying there still hasnt been a payment since June 2nd.. Half the stuff he tells me is lies and he really doesnt have much to do with our son..We did have a schedule where he would get him every Saturday all day. But then that stopped and he didnt see him for months. Now he calls and wants to see him that day and sometimes i already have plans. then he tells me that he'll call me in a couple days and asks if he can take him, i say yeah thats fine but then i dont hear from him for weeks after. He was supposed to take him friday of last week and i havent heard from him since tuesday of last week.. Im getting pretty fed up with it. My son doesnt deserve it..