I don't think this is possible?! The whole point of a
service interval is that it is designed around the needs of the car/engine.
I don't think you can just change to longer
service intervals and pay a little bit more.
You could have just leave it longer between services if you wanted, but that's probably not recommended. You'll increase engine wear, not notice potential problems until they become real problems etc.
The only real option would be to swap for a car that requires less frequent
servicing. BUt that will probably cost you too.