Car drives fine for about 30 minutes then starts shifting in and out of overdrive and sometimes doesn't shift gears at all. I took it to Advanced Auto Parts since the check engine light was on and they check it for free. This is what he told me: "code p0743(or p0734) 4th gear ratio incorrect, transmission control module." So I contacted a dealership near me and they told me to replace this would total $915. They told me it was a dealership part and I could only get it from them and only they could work on it because nobody else knew how and only they could reprogram it after it's done. Is this true? Can I get this done cheaper?