won't shift above second gear - fault codes P0700 and P0763

I have the vehicle listed above with transmission problems. It's been acting twitchy for the last several months. It gets stuck in "limp mode" it won't shift above second gear. Sometimes it pulls fault codes P0700 and P0763. When this happens the gear indicator on the instrument panel displays"-". I've tried disconnecting and reconnecting the battery which will sometimes solves the problem. I've also had the software updated by the dealer. It's been an intermittent problem up until now. But now it's permanent. Does this look like a major problem?