Power Steering Light On problems of the 2005 BMW Z4

Have had the car for several years and have noticed a steering issue that seems to be getting worse. I researched this on multiple forums and it appears that there are numerous examples of similar problems. Most relate to issues in hot tempatures, mine is more related to speed. Problem was very noticable last evening at 70 degrees. Here are the symptoms. . . At low speeds (under 20mph) steering is very light and smooth, no issues at all. As speed increases, the steering gets heavier (as it should) but develops a "detent" at straight center. The faster the speed, the more effort needed to overcome the detent resistance, to the point that it becomes easy to oversteer the car. This can be real scary during avoidance maneuvers and quick lane changes. I have had my car worked on for other service and the mechanic also noticed the issue as it was driven to have the wheels aliened.

I was driving the car at approximately 45 mph and the car sterring got stiff. I couldn't control it. The power steering malfunction light came on. I got very concerned and somehow made it home. Luckily I was close to home when it happened. The car after turning off and turning back on got normal. The symptom did not come back for 2 days but then came right back on. Now I'm scared to drive this car. This is so dangerous and can cause an accident. I did some research and found I'm not the only one with this problem. A lot of other people had the same issue. BMW should fix this issue at no cost and there should be a recal on this.