If it had been at least a double pack!

Instead of a twin pack came a single cartridge. I sat down with the supplier and noted this but .......... no response !!!! No explanation. No Apology.
Conclusion: I have now paid more than if I had immediately ordered as a single pack for a single cartridge.
Great business practices. Thus one gets a simple way also money in the cash register.
This is already the second sellers with whom one can not be happy and I wonder whether it should not also be the last.