AEG 4040w seems to overheat

Customer has asked me to lok at her AEG dishwasher 4040W PNC 91123201401, she says it seems to have burnt her glassware crockery & saucepans etc, when i asked her what temp she had selected, she looked at D’W & said no temp’ buttons were selected, her wash seemed to be clean enough but seems to be heat damaged. From memory i think this machine has two stats in base of machine on lh & rh side. What i want to know is do these normally gave rise to overheating or is it likely to be a timer sticking. The machine is 7 years old.