Thank you, emsr2d2, billmcd, and SoothingDave.
How about:
1. The company offers a prompt and efficient shipping service.
2. The company offers prompt and efficient shipping service.
3. The company offers prompt and efficient shipping services.
By the way, in the case of "after-sale service," I believe that Americans would say:
1. The company offers good after-sale service.
but not
2. The company offers a good after-sale service.
or
3. The company offers good after-sale services.
Is my udnerstanding correct?