ISUZU BAD SERVICE, BAD COMMUNICATION

I have sent my vehicle in for a check-up on the gearbox thats still under warranty. My vehicle went in on Tuesday, its Friday already with me trying to following up every single day. I have phoned several times in order to get to know whats happening... still no reply. My vehicle is still under warranty and according to my knowledge buying this vehicle secondhand, they told me all services was done and everything was perfect. Its now 13:30 and for the first time this week, ISUZU HEAD OFFICE phoned to say... the claim cant be processed. WARRANTY IS VALID UNTILL 120 000KM's I am furious!!!!! My vehicle must be repaired!! As its still under warranty.