What do fault codes mean & how to fix them on Zafira 1.8 2000?

Hi, have engine misfire on my 1.8 2000 Zafira, engine light on & also traction control light, Had it diagnosed the fault that come up are : IGNITION COIL PRIMARY/SECONDARY B & IGNITION COIL PRIMARY/SECONDARY D, Please could someone help as i have replaced the coil pack twice but still says the same & still have same problems...!!!

What else would cause these problems as i really don't have any more money to waste on it. It took me 3 months to save for coil pack, which was from vauxcentre on ebay was only £49 delivered for new one..