Unwanted free with gold ad on my comic

Hi I recently uploaded my comic to globalcomix and intentionally had it set to be a free comic to read. When I uploaded my comic chapter today a free with gold add was randomly added to my chapter. Is this a bug? Can something be done about this? I enjoy globalcomix and I enjoy posting here, I don't want to ward off any potential readers because of an unwanted free with gold ad being placed on my chapter uploads.