Add link to Site; Adjust CMS.

We're a survey company and we need a link added to our home page that directs visitors to our website to? survey site.? A few months ago we hired a firm to add the link to our site; this link went to a webpage on our site that in turn listed links to various surveys on Surveymonkey. This all worked fine until we used our content management system to update our site; when we did this the link on the home page disappeared. The vendor uploaded it again but once again when we updated the site using our content management system, the link disappeared. We need to find a way to put the link on our home page in such a way so that the content management system that we use does not cause it to vanish every time we update the site with new content. We are unsure how to do this but we know that we once tried to put a link to a newsletter on our site and this vanished a few times until a consultant explained to us that we had to use a particular technique in putting it up and then it would not vanish. Indeed, it did not. We now need a firm to do the same with the new link that we need on our home page; to put it up in such a way that our content management system does not cause it to vanish.