Sounds like your rear one has the same problem mine had. The regulator clip was broken so I replaced it.
Cost $11 for a clip and about an hour to change it, pretty easy and there's plenty of instructions on how to do it online.
http://www.ebay.com.au/itm/Window-Re...oAAOSwHnFVusQB
Your front sounds like it may be electrical, so check all the wiring. You may need a compete unit but there not to exy on ebay.