v6 auto gearbox

hi first time on so bear with me, my auto gearbox has started changing gear very harshly on 2nd & 3rd gear going up & coming down the gears,
also when you drop it into drive it lurchs forward, i,ve had the gearbox serviced but its still the same, any suggestions or advice would be greatly appreciated,
regards r.b

V6 auto series???
Wot series is it?