Well after many hours checking the vacuum pipes, and after watching a few videos on youtube about the peugeot engine I put a tube into the turbo and sprayed Mr Muscle into it having read the actuator arm not moving much is a sign of the vanes? in the turbo being coaked up. I may get a few of the terms wrong as its my brother who is more mechanically competent! After an hour of letting it dissolve the crud and moving the arm via a big syringe we put it back together. I deleted the codes and let it idle until it reached normal operating temperature. Several spins around the block theres no limp mode, no turbo warning light and also no message saying transmittion service needed. Its acceleration is back and it went up to 50 with no over revving.
So I think I can conclude it looks fixed, the problem appears to be the car not getting enough pressure to change gear due to the crud and then going into limp mode as a protection of the gearbox. So the three times I changed the auto transmittion fluid (which was needed as it was black) was treating the sympton rather than the actual problem, and the transmittion service required message after the oil had been changed was a red herring!
ps thanks to all who gave advice, much appreciated