Request to attend to vehicle runnig hot not heeded

I experienced that my Opel Corsa UTE 1.4 Sport started running hot after the 135,000km service. I called the service centre at CMH Boksburg regarding this, and was telephonically assured that it is normal up to 100 degrees C. At 150,000km service, I again logged a concern about this vehicle running hot. Nothing was done by CMH Boksburg about my complaint. I recently took this vehicle to Peter James Motors in Springs to replace the oil pressure switch. I was called by the workshop to inform me that my bakkie is running hot!!. As a result the thermostat was replaced, and now my vehicle is again running at normal temperature. I wish to know, if there are any latent engine failures due to overheating, if either General Motors or CMH Boksburg is going to make good on this negligence. My original request was when the vehicle was still under guarantee and my concern registered on the 150,000km service job card