Wrong supp**** injectors

I bought x4 1600 Bosch injectors from Dictator last year August 2017 for my rotary engine. They supp**** me with compressed natural gas (cng) injectors. I am not a fuel specialist and they said it will work for me. I asked them if i could return them if they are not correct and they said they would do so and is not a problem. After my engine builder and numerous other injector specialists said that those specific injectors will not work, as it is not for high performance petrol engines, i had no choice to return them. After a heavy discussion at their offices and initially refused to take it back they agreed to take them back but is going to charge me a 25% handling fee, even though they supp**** me the wrong injectors in the first place.