how to clean thermal curtains

[kjaysmum]

Hello, I have returned from an overseas trip to find my thermal curtains have a watermark on them and also mildew!
I am getting conflicting advice on how to clean them. Can I dry clean or not? If not any advice on how to get them clean?
Thanks

I just spoke to a dry cleaning company and they will cost alot to have professionally cleaned and they can't guarantee they wont get ruined, very frustrating as they are well old and in rented accommodation on which we have a pretty large bond!!which I can see fading into the distance along with the curtains, oops