MB92

Hi all im new here but would really apriciate help

Recently my car started wandering left and right at motorway speeds but it started getting worse recently and car feels unstable at lower speeds now too especially when accelerating or going over bumps and its tramlining badly but its still bad even on very smooth roads and have to constantly correct the wheel especially when its raining or windy.

I Have replaced all 4 tyres and got 4 wheel alignment and that didnt help and i also checked all the bushes and all seem fine. Tried with different tyre pressures from 30 psi all the way to 50 but it hasnt made much difference, when going round a slight bend with bumps on it the car feels like its swimming sideways towards the outside

Im doing 80 mile round trip to work a day so its really tireding and dangerous at times.

Car is Audi A3 2008 1.6 102ps
80k miles (mostly motorway)

Thanks for help if you have any ideas