Barre à serviettes murale 16,5" Boxe 8412000.002

I recently purchased an American Standard 16.5 boxe undermount bathroom sink towel bar. Originally I was so excited for this solution for our bathroom. Unfortunately both of the rubber plugs failed and I had to return it and I was told that replacement parts are unavailable. If there is any way that this will work I'll gladly reorder another one. Visually, the towel bar appeared to be rather old. So old that the rubber pieces (that hold the bar and lock it into place) were stiff and dried out. Another observation was, the tape used on the parts bag had yellowed and was brittle. I really want this to work and I'm looking for some helpful advice, direction and a solution to finish my project.