Spaxs

Morning everybody, I am in need for help as it seems I can’t order spare parts for my MP95e in Germany. I am looking for a smaller notch or as an alternative a bigger sighter. A distributor in Germany already provided me an adjustable notch which was not fitting to the gun unfortunately. ATM I am having a sight in size 4.0 at the front of my gun. I am looking for a bigger one. Anybody able to help me in here? Thx and sorry for my bad English. Matt