Mazda has no compression to valve 2 had new plugs fitted an still the same garag on 2004 Mazda RX-8

Garage av told me I need a new engine at a cost of 2000 but car still drives but misfires could it be something else

Asked by for the 2004 Mazda RX-8
no compression is no compression. is it valve related or piston ring related?