Global fashion house Chanel has forced a small Australian chocolate maker to change its branding after it claimed a trademark infringement on its No.5 perfume.

A letter from Chanel's lawyers was the last thing that Chocolate @ No.5 owner Alison Peck expected when she set up her company. After all, her business is a "two-man show," named after its address – 5 Main Street Hahndorf, a village in the Adelaide Hills – and makes chocolate, not perfume or haute couture.

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Her company would have most likely gone unnoticed by the multinational fashion giant had it not applied for a trademark registration.

Last year, another chocolate maker - this one from Melbourne - tagged a photo on social media network Instagram using the same name as Ms Peck's operation.