How should I go about getting my air conditioning re-gas done under warranty?

We have a two year old SEAT Ibiza which needed an air conditioning re-gas, costing £70 as it wasn't covered by warranty. Nine months down the line it has failed again. By my reckoning, it has a leak which they should be able to see because they they put blue dye in last time. I have a feeling that they will try and fob me off with another re-gas. What's my best argument to get this fixed under warranty?
If you do not use the a/c regularly (which means right through the winter), the seals of the system that are kept gas tight by lubricants suspended in the gas will begin to dry out and leak. The simple act of using the a/c for 10 minutes every week keeps the system gas tight.
Answered by Honest John on

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