Websites hosted with Afrihost keep getting hacked

We have 2 dedicated servers with Afrihost with about 40 domains hosted. Some sites are custom made, some Wordpress sites and some that are not in use and have no files on the server. All these sites are being hacked and phishing pages for the American bank [URL Removed] are being put on our server/ sites almost on a daily basis. I have requested numerous times that they investigate and increase the security of the servers by firewall/ any means necessary but nothing has been done. Our sites continue to be hacked. They suggested a developer look at the sites and software that is installed on the server, but the software installed on the server is Afrihost's software.