Have the clutch slave cylinder checked out, my 2008 s5 had same issue. The slave is external to the gearbox so fairly easy access https://www.autodoc.co.uk/sachs/1228970?gshp=1&gclid=EAIaIQobChMI9oSXyJL_8gIViJ7tCh3Vrw3cEAQYASABEgK8jPD_BwE check your fitment.
