@Sunrise: If you want to stay or even grow on the Swiss Market you have to learn one specific point about Swiss people: they are very sensitive about legal imperfections, even this is only about one CHF. They will going to sue you about 1 CHF if they are convinced they are right.
So for sure your current strategy of ignorance will not work here.
In Switzerland we also know the strategy of GOODWILL. This may come to the rescue here, and even will be cost effective for sure.
Just compare the cost (SUNK COST in both cases).
The goodwill cost in such cases may be 100…200 CHF in 95% of all cases.
The legal cost will not be below 1000 CHF in 95% of all cases, not implying the damage of reputation. Restoring a spoilt repution costs not below 10k in advertizing and promotion efforts, as a cautious estimation.
So if I were you, this is a nobrainer what to do in each case. Consider this cost as marketing cost, and that is essentially what it is.
With your current policy you actually do the contrary: All the money you invest into marketing and promotion is rendered void and wasted by this kind of customer complaint handling from your side.
So better STOP all promotion efforts right now, as this money is completely wasted until you have cleaned your backyard. Just a little advice from nobody. LISTEN or GO. Choose.
