Very low capacity of supposedly XXL black cartridge

I've ordered pack of color and black XXL cartridges (Set Alternativ HP Patronen 300xl Schwarz +
Color). Black cartridge is already not functioning / empty. Since beginning my printer was reporting black cartridge is low on ink. I thought since this is not an original there might be such "reporting" issues or similar. I've printed less than 50 pages not more as I print quite rarely. I thought this will last at least for a year not 2-3 months. Furthermore my printer has just started reporting color cartridge is low on ink as well. Not satisified.