We love Cookies. Set/Remove/Expire all so simple. Used correctly they can help with all sorts of scenarios and can save a huge amount of unnecessary effort. It’s worth insuring your Users have Cookies enabled by using the Browser component to display an Alert and hide any content if the User has Cookies disabled, prompting them to enable Cookies, and preventing unnecessary reports of errors by Users with Cookies disabled. We usually apply a ‘CookieCheck’ Div enclosing the primary content area. Then this way if the Users Cookie permissions are set to disabled no content is displayed aside from the aforementioned Alert. 
Glad you have it sorted and am sure your Client will be happy with the result!