Service (λειτουργιας). Old word from λεως (people, λαος), λειτος like δημοσιος, public, and εργον, work. So public service either in worship to God (Luke 1:23) or benefaction to others (2. Corinthians 9:12; Philippians 2:30). Our word liturgy is this word.

Filleth up (εστιν προσαναπληρουσα). Present active periphrastic indicative of double compound verb προσαναπληροω, Koine word, here and 2. Corinthians 11:9 only in N.T., to fill up by adding to. The Corinthians simply added to the total from others.

Unto God (τω θεω). Dative case and with a certain suddenness as at close of verse 2. Corinthians 9:11, really a parenthesis between in the somewhat tangled sentence.