Toyota heavy as hell on petrol

<p>In2014 i bought a 1.6corrola sprinter at upington toyota I took it now a few times to them for this problem the last time they said that my no 3 piston havent got compression and have to open the engin just a few hours later they phoned me an told me it was only the plug the porselyn on the plug was broken and they replaced the plugs and gave the car back to me Well the problem is still there very heyvy on petrol What stand me to do as my warranty expire in 2 months</p>