Bad service and guarantee from Ryobi

I bought a Ryobi petrol lawn mower about a year ago and only used it for one season. This year when I started it for the first time it ran for a while and then stopped. Could not get it started. I have maintained it according to the manufacturers recommendations as in the manual and even only used original oils and parts. When I send it in for repairs as it was still under guarantee I was slapped with a bill of more than R1200. I queried this as it was still under guarantee and it was send for a second evaluation and it came down to R700. When I asked them why the piston, rings, valves and conrod which they apparently had to replace was not covered I was ignored at told that I should bring in the lawn mower more frequently for a service. When I asked why these requirements is not in the owners manual the Rep refused to talk to me or phone me back.