bad service and incompetence

i bought a pre used car at Hyundai last year November, only to find out they sold me the car without renewing the license disk, i hand to pay for it and penalties at thr traffic department. the manager promised that they will refund me, its been 3 weeks everytime is a story,i have been told every time i must submit this then i do, it becomes a story after, i waste my petrol going to them every time it's empty promises