Red Power Steering Warning Light

We were holidaying in the Italian Alps five weeks ago when, partway round a hairpin bend, the power steering warning light came on red, changed to amber within a minute and then went off shortly after. It did the same (not going round a corner this time) a week later and switched on and off intermittently all the way home. The power steering shut down whenever the light came on.

The code given was for steering angle sensor failure which my local garage duly replaced. We then had three weeks of hassle-free driving until two days ago when the warning light came on again. This time, however, the light comes on after 15 to 20 minutes of driving and then stays on and it has done this consistently on three occasions now. The code still reads steering angle sensor.

My local garage is stumped for solutions - can anyone help?

Many thanks