Strange circumstances

I bought a car from beginning of August. Did the test drive thing and liked what i have seen. No lights on on the dssh board happy with the dekra report. So i bought it.told the salesman prepare the papers i will be back in the morning to pay and collect the car. The next everything went well. Collected the car. On the way out of the premises suddely the engine management abs & tracktion control light came on. The next day i took it for a dianostic scan. It come up with a YAW SENSOR failure. So i took it to wiiliams hunt(they the agent for hummers). They where looking for the yaw sensor but could not find one. But found the place and the harness &plug where it supposed to be.i thought WOW . One day no lights on on the dash abs working just fine.next day collect the car allnlights on no abs? Now what? The only explanarion is someone took it out !! Thats in my book is theft. Now i need a explanation from we buy cars or i have no choice and open a case of theft at the police station. .