The phrase "through agency of" is a formal way of expressing that something was done or achieved with the help or intervention of someone or something else. There are several synonyms for this phrase, including "by means of," "via," "with the aid of," "using," "through the involvement of," and "by way of." Each of these synonyms can be used interchangeably with "through agency of" to convey the same idea of assistance, facilitation, or mediation in accomplishing a particular task or goal. Using these synonyms can help to vary your language and avoid repetition in your writing.