Usage: On behalf of is sometimes wrongly used where on the part of is intended. The distinction is that on behalf of someone means 'for someone's benefit' or 'representing someone', while on the part of someone can be roughly paraphrased as 'by someone'. So, the following example is incorrect: another act of apparent negligence, this time not on behalf of the company itself, but on behalf of its banker, when what was meant was there was negligence by the company's banker

Acá dice que se suele utilizar incorrectamente y que debería ser "por los servicios gestionados", pero para evitar la personificación creo que tu opción "como parte de los servicios gestionados" es la mejor.