Retrofit GRA in A2

Would like to retrofit a GRA in my wife’s A2 (A2 1.4 petrol engine, year 09/2005). Apparently the replacement of the turn signal switch and subsequent activation in the control unit is enough. Must the steering wheel be removed or can you get it like that to tap the turn signal lever? If the steering wheel has to be dismantled, I don’t want to do the replacement myself because of the airbag. Can / can any free workshop install airbags? what is the cost of the GRA retrofit at Audi? honor? Thank you very much Lupo