U can use you share IP for now. Cause you just create ur account on Fiverr. But as soon as possible u need a real IP. If u don't use real IP your Fiverr Account will be band for not using real IP.
Is it because of the quality of the delivery? If yes, sort it out with him. If he reports you for poor quality work, you may get a warning. So no matter the cause, Fiverr recommends that you seek amicable settlement first before contacting support.