Thermistor Mixup

Hi I have received my printer today, and followed the setup instructions as far as "Test the extruder with initial burn-in temperature" when I attempt this the extruder does indeed heat up but the temperature rise is reported in Repetier as the Flatbed and not the Extruder. Very quickly at about 130 degrees Repetier enters error mode because it thinks the bed is too hot, but of course the bed isn't hot at all. So I think the thermistor for the bed and the extruder have been mixed up in my unit, will this require rewire if so can you provide detailed instructions for this, or are you prepared to replace the unit? So unhappy to wait so long as a backer then despite QA tests at your end, this problem should slip through.