That's a rough issue for sure, If they won't resolve the IP not even a trace route would work.
Perhaps you can show your ISP that outside their network it works but while on it you can't even trace route
https://tools.keycdn.com/traceroute
You could always check out a free wordpress:
https://wordpress.com/free/?utm_source=google&utm_campaign=google_wpcom_search_brand_desktop_us_en&utm_medium=paid_search&keyword=%2Bfree%20%2Bwordpress&creative=327272467836&campaignid=998785131&adgroupid=53026925687&matchtype=b&device=c&network=g&targetid=kwd-28925771378&gclsrc=aw.ds&gclid=Cj0KCQjwpdqDBhCSARIsAEUJ0hOj-tNOfoU7pZ9ZAvywVpiTe0WQxU4ap7G_1da022JrovwVySA977caAoyfEALw_wcB