The Collaborative International Dictionary of English v.0.48:
Disservice \Dis*serv"ice\, n. [Pref. dis- + service: cf. F. desservice.] Injury; mischief. [1913 Webster] We shall rather perform good offices unto truth than any disservice unto their relators. --Sir T. Browne. [1913 Webster]WordNet (r) 3.0 (2006):
disservice n 1: an act intended to help that turns out badly; "he did them a disservice" [syn: disservice, ill service, ill turn] [ant: service]