Razvan Dobie

Hi I bought am GLC Coupe 250 in august 2019 and in october i felt some kicks when i slow to make a turn like 15km/h and when i press the acceleration pedal i felt a kick so i went to an specialized shop that repairs only mercedes cars and i found out that i had to chande the TCU due some fails and what ever.
Before changing the TCU in sport plus mode in some hi revs when it change between gears it had that "fart" sound
After that nothing absolutely nothing , i went to that service but they don't know how to do that or they don't want to do it ,
Does any one know how to activate that function again