Why has the air con gas in my Nissan X-Trail already run out?

My Nissan X-Trail is under two years old and has done less than 8000 miles. The air con isn't working properly and I've been told by the Nissan dealer that all of the gas may have been used up and I need to pay £250 for a refill (it's 'new' gas so more expensive). I've waited for the last month to check that it isn't a leak as advised by them. Is it really reasonable that it has lasted such a short period?
Standard problem because of the new R1234yf refrigerant used in place of the old R134a, by request of an EC Directive. It's flammable, it leaks and it costs four times as much to re-gas.
Answered by Honest John on

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