Pathetic service from Hyundai Springfield

I am absolutely shocked at the pathetic service I received from Hyundai Springfield. My car was booked in for service last year and they did not log the service on their system neither did they stamp my service book.Now I am being told I lose my 7 year warranty on the car because of this.I have made numerous calls to them and was told the Manager would call me back but still nobody has contacted me. I even asked them to check the footage but the service guy said they only keep footage for 7 days and had such a bad attitude over the phone. I would never want to deal with them again.