Engine Light

I bought a Ford Focus 2.0 Sports in October 2012 and have always been servicing it in Welkom as it was on their Maintenance Plan. In 2013 the car started to show the engine light on the dashboard after it came back from service and after calling the Workshop Manager he said as it was on Saturday I must drive it and brought it back on Monday if it does not turn off. The light was reported every time the vehicle went for service and was told to bring it back immediately it comes on but was difficult because I am staying 75 km from Welkom. I once take to the Human Auto in Welkom and had to pay in the region of R 375.00 for them to put it on the computer and the report was something of oxygen was faulty by that time. Every time it went for service the same issue was reported until I decided to take it to the other garage were they told me that the oxygen sensor was faulty and should have been replaced long time ago because it increases my petrol consumption. I not satisfied because I have lot of money on petrol and didn't get assistance whist my car was still under guaranty now I have to repair it on my cost.