Start stop system out of operation

Hello Yeti friends, bought at our Yeti (1.2TSI 110PS EZ 6/16 km stand 22000 as an exhibition vehicle) is the Start Stop function out of operation (it is always displayed this way). The workshop takes this back to the low mileage and short distance operation and first charged the battery. Then there was also a week then the problem again. Last week the Yeti was also there on holiday trip – fully charged- short time full function, hardly at home again out of function. M In one opinion, the battery has a defect or it is not fully charged. The workshop is somewhat concerned with a problem solution and spoke of possible “software updates”. The warranty runs out next month and I would need some advice from you so that the car remains as error-free as it has been driven up to now. The Start/Stop automatic is not vital that I know of course, but if available it should also work, thank you in advance for the answers, Greetings Hilma rV40