First do a search on steering box adjustment
If adjustment of your steering box doesn't sort things out I'd then try replacing the sterring linkage, idler arm and dampener.
That's the order in which I should have renovated my 126's steering. All of those replacement parts dramatically improved the feel of my car. However, there was still quite a bit of play in the steering wheel which required adjustment via the steering box. Adjustment is free and it doesn't sound as if your car has an extreme amount of mileage. The idler arm is located towards the rear of the passenger's side ofthe engine. The arm links to the center link which in turn connects to the steering arms. Replacing all these parts are fairly easy to install yourself, just make sure to measure the threads of the steering linkage in order to preserve alignment. There is a decent exploded view of your car's suspension at the performance products website. Buy your parts from fastlane though. Good luck!