It's exactly the same for me. It doesn't work and, in my view, it's a rip-off. But at least the product is very good. It would be very nice if Galaxus would give us a 20Fr. Voucher as a replacement for the unfulfilled promise.
You can find replacement brushes on the Braun.de website. Simply enter "brushes" as a search term. Then select your desired product and it will redirect you to the dealer's site. Simply change the country to "Switzerland".
Retailers are e.g. Brack.ch or Inter Discount.
No, it cannot be used while charging. It takes about 1 - 1 1/2 h until fully charged. However, once charged I use it for legs, arms, armpits and to epilate the intimate are without having to recharge it in between.