RCA Cables and Closed Captions?

[indieFan]

Does anyone know if RCA cables can transmit closed captions? I have an SD cable box (not HD) that is now connected via RCA cables instead of the coax cable; and, I'm not able to figure out how to get the closed captions.

The cable company insists that I need to upgrade to an HD cable box to receive the closed captions. I do not want to do this.

The coax cable is not an option either due to the fact that the picture becomes extremely snowy. Cable tech that came out explained that the connector on the tv is likely loose due to the twisting motion and lack of strain relief on the component(s) for coax connectors. I had already tried switching the box with the one in the bedroom and had the same issue.

Thank you,
indieFan