Why does the diff fluid need changing in my 26,000-mile-old Honda CR-V?

I have a second generation 2005 Honda CR-V 2.0ES. I felt a strange 'rubbing sound' on either full lock. After a diagnostic charge of £48 I was told the rear diff needed flushing out and a fluid change at a cost of £210. This seems excessive on a car that's only done 26,000 miles from new. Can you comment please?
That is a standard maintenance item on the otherwise exceptionally reliable CR-V. It has a rear axle breather and over time moisture can get in through it and contaminate the diff oil.
Answered by Honest John on

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