I have a 51 plate Renault Clio 1.5 DCi 65 that is permanently showing the glowplug light. It has been to the garage to have the glowplugs and glowplug relay replaced. Each time it has been in to get fixed, it has come out fine for the first couple of days but then the glowplugs have failed again within a week. Can anyone advise what it might be? By the way, the fault code that came up from the garage was a glowplug relay fault but that has been replaced to no avail. Please help.