Very happy with my new MINI Clubman, except . . .

Fairly minor thing, but I noticed that the front plastic fenders were getting stained with a fluid coming out of the hood. Tried to clean it off with a couple different gentles cleaners but the surface was marred. Dealer said to just wipe it off, but then said they would replace the fenders when I got a little pissy about it (if it just wiped off I wouldn't have taken it to the dealer!). The fluid is still leaking out, so I told them not to install the new fenders yet. The dealer said they would only replace them once and had not fix to keep it from leaking.

Now that I have googled this some, I see it is a problem with MINIs going back to at least 2008 and also is a problem with some BMW cars. Why do they keep doing the same stupid procedure if it ultimately damages the car?

Anyway, I am afraid I will be dealing with this for a while even if I have the fenders replaced so does anyone have any specific cleaning suggestions? I found one guy who said use WD40 but that seems odd. Armorall doesn't work. Some bug cleaner thing I have doesn't work.

Thanks.