Corsa b Motor 1.2L. 45 Ps central syringe

Hi guys, need your advice. My engine really eats the spark plug on the third cylinder. I bought the car 3 months ago. Changed the spark plugs,and I noticed that on the third cylinder the candle was completely burnt out. A month later I died of the electronic ignition coil, the third cylinder no longer got juice. Yesterday he ran restless, removed the candles and the candle from the third cylinder is attacked again. is black. I am finished with my advice. He burns no oil, compression is top. Who can help me ????????