A little update in case anyone run into the same issue.
I just damaged the oil sump in question as it is quite low espacially on a 2006 roadster 4 seaters. The oil was starting to leak from the sump as a result.
Just as Dave stated it and following his advices, it is indeed possible to find this oil sump on Ebay. Thanks Dave!
And yes, I have been to a Ford dealer first, but they couldn't order it as the engine is not on their list in France)...
