Evo 3 gears broken

So I ride approx. 50KM per trip a day / min. 3 days a week = 150+ KM per week.

How long is the expected life expectancy of an average Strida Sturmey Archer’s KS box?

Since I can’t perform maintenance on it myself or by the Bike Shop (who is the authorised reseller for Strida) - what makes sense? It is easier to just BUY a NEW KS Box?

Is that possible and how much does it cost?