Thanks to all the responses.

Yes, I used a scan tool and got the car up to 40°C during the last fill after doing the provisional fill. After the first fill I went though all the gears for 5 seconds then stopped.

I got some more fluid in, did the same but this time went through the gears a few times holding each for about 5 secs. I also went into manual mode from Drive and went through a few gears there also.

The car only took 5.5L of fluid and seemed about a litre short of what came out but no matter what I tried I couldn't get any more in.

I did make a mistake and shut the car off between fills so I'm hoping that is the issue and with the car running I'll get more fluid in.

God I really hope that's all the problem is