Difference in exchange rate

I am reposting my comment here. I've been informed that there is £7,000 left in my Marie Curie fellowship due to a difference in the exchange rate. I was told that Research Operations took this money for themselves as an 'administration fee'. Some of you have said that this amount should have been given back to me. My query is, would this be documented anywhere I can use as evidence, is it a clause in the EU/host instituion contract? It relates to the old fellowship Marie Curie International Outgoing. I have only just been informed they have done this. Another member told me that once a contract ends, the applied exchange rate is compared to the real one based on the historical exchange rate data and they compensate the fellow. Many thanks in advance.