Corsa-B.uk - Vauxhall, Opel and Holden Corsa B Owners Club

Just gone to change the oil in my x12xe. Only to find the previous owner or mechanic or whoever has over-tightened the plug. I've tried everything to move it! Tried whilst engine was hot, cold, tried mole grips, pliers and the T45 torx bit! Won't budge, don't wanna be causing damage or anything :/. I don't really wanna leave the oil change much longer, it's been around 11k now since the last one in August 2011, that and I've only had the car since February of this year lol. Any suggestions?

try soaking it abit of WD40 an leave for a while if its that bad your gonna have too change the whole sump