Can someone tell me how can I change my test centre or can I change it?

I am from Bahawalpur and Islamabad is very away from my home when I applied in COMSATS Islamabad they issued me a roll no slip in which my test will take place in Islamabad and I cannot go there it's pretty hard I wonder if they can change it their vahari campus somehow but I don't know how can I change it or request them to do it if it's possible..Is there anyone who can drag me through it?plz tell