hi all, just been to a smeg hob touch type mod se 2640 tc1 ser 90423 cust says twice in the last 3 weeks all the hotplates have shown the no 8 and the on light and lock light have all been on together although no plates have been hot.. this has been resolved by switching it off at the wall for 30 mins or so.. it happened when the oven below was on but not the hob if that means anything both connected to same supply.. is it an error code? or just ?? any help appreciated thanks