The agency believes the payments it has made to the AAR, roughly £14,000 a year, were too high for the number of pitches it was included on.
A JWT spokesman said: "Over the past three years, JWT has taken part in 48 pitches, none of which have come from the AAR."
Kerry Glazer, the managing director of the AAR, said: "Given how busy we have been this year on client reviews, it is disappointing JWT has decided that we can not help it in its marketing and new-business efforts. We wish it every success."
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