You can file a complaint with the "Federal ministry for digital transformation" (formed this year). It does actually work, but it's a lengthy process.
I did force my cell phone carrier to grant me proper 4G speeds last year, after spending many hours with their help line and ultimately complaining to the (then) ministry of transportation and digital infrastructure.
I did force my cell phone carrier to grant me proper 4G speeds last year, after spending many hours with their help line and ultimately complaining to the (then) ministry of transportation and digital infrastructure.