2hrs is a ridiculous time limit. Some posterior babies don't turn until near the pushing stage of labour or later - my 2nd posterior birth saw me pushing while the assisting nurse was pressing on the right side of my belly to encourage him to turn. You just can't put a time limit on it, particularly in a VBAC where you need to let your body do it's own thing in it's own time. Work with your body in positions favourable to gravity (upright, reclining forwards, even sitting on the loo/fitball) Laying on your back will hamper the progress you make as baby can't descend and turn properly.