1) how long have you owned the car? If you're a new owner, proceed to question two-
2) do you have a nikasil block? If yes, decide whether you want to replace the engine block, or part out the car and cut your losses.
Look up casting numbers, searching for your engine and that term- I'll throw you a bone-- the casting number is beside the block coolant drain bolt, on the passenger side (US LHD model).
Start here before lifting a finger on anything else.
It's not what you buy, it's what you build- Unknown
EN90283 - Stabled for HG repair
DH06247 - Running like a champ