Hello and Thank You for using Just Answer. I am sorry to hear about the problems that you are experiencing with your son. His manifestation of disrespect to you is a sign of his immaturity. He has all of theses freedom now away while away from you in college. He is given money as well. He has it made and he knows that. Who pays for his college? Where does he live while in school? Do you pay the note on his car?
Since he is completely ignoring you, the next step is to write him a letter. Put all of your feelings out there. Tell him how you love him dearly but do not appreciate the lack of respect that he has for you. Ask him what have you done wrong? Then wait a while...weeks or even months and see what happens. It has often been said that "Time heals all wounds." He may come around and realize that he truly needs you. In the meantime, keep his phone service suspended. Decrease the amount of money that you send to him. Let your letter speak for itself. He is probably being influenced by his girlfriend and her family right now.
Also, it would help if his dad is on your side with the issues as well. Hopefully, he still has a relationship with him.
If you need more advice, just ask.