Hi Bob, sorry about your problems. First thought, "I would be pi$$ed off an taking it back to them". If you drove off an home , they have " deniability ". Stuck in 1st leads me to think" limp mode", but the hard slam into gear is not a symptom. Unless you have a transmission or motor mount completely broken. Does the thump, shake the car, like something hit the underneath of it? Or is it a metal grinding noise? Do you have a OBDll code reader.?If not ,all most any parts store will have one an will gladly help. Those codes will also help us, to diagnose what's going on. Remove your battery cables for 20 mins , reconnect, give it a try. This is not a solution, but a starting point. Keep us posted an let us know what your doing , so we can help an follow along.