Auto Gearbox Clunky

[Bigboyzone]

Hi I have a 2010 petrol auto 2.0L 200bhp Ecoboost. It has 70k on the clock. The gear changing isn't the smoothest in the world but what mostly worries me is when coming to a stop at a junction the last gear change down goes with a bang and feels like you have just hit something. This is intermittent but seems to improve when the engine has warmed up.

From what I can gather from other threads I suspect an oil and filter change may help. I have no problem with that however because the change downs can be quite violent on occasion I am concerned that there may be more to it than that.

Any thought would be appreciated.