Engine light on for the 3rd time

i have a serius problem with my ford focus engine light problem again for the 3rd time within 4 months, i just collected the car on monday the 15/04/2019 ford pta central bosman st, today when driving to working the light is back again this guys made me to pay R1900 for the engine thats under warranty this car is 2 years and 4 months. the service am getting for ford is very poor and am currently unhappy with this matter kindly assist me to resolve this