If you haven't heard from the company, you will probably never get it CC.
I had a similar issue with the old
Transformers television series. They had the whole series on DVD, but not captioned. It was made by a Canadian company so they don't follow CC stuff. I contacted them after each season was released and they gave me the same response... "Sorry, we aren't doing closed captioning right now... but we will take your suggestion into consideration for future products. Thanks you."