Defrosting windows...

Lacquer thinner may distort and craze the clear plastic. Don't know if pure ammonia and a q tip will remove Vallejo. It works on many acrylics including Tamiya's which is a pretty strong paint. I was gonna suggest Future but you tried it so maybe a couple more Future coats will work.

Raven Morpheus

 .  Applying olive oil worked wonders for my 1/48 Huey when I sprayed it with Humbrol rattle can matt varnish and that frosted, although I don't really like the greasy layer it left behind but I did over do it a little.

Oh well I live and learn, I thought I was safe using an airbrush for matt varnish but I think from now on I'll apply matt varnish by hand, especially where I can't (or have forgotten to) mask clear parts!

Olive oil ?!?  well even if the results are not as you want;  it will smell better in your model room,  fer a while  

Good Luck and  Windex will remove Future  just in case

Well, it's been known to happen! 

http://cs.finescale.com/fsm/modeling_subjects/f/2/t/154360.aspx

Try soaking it in isopropyl alcohol.

IPA doesn't remove Vallejo.  You should use denatured alcohol or lacquer thinner.

Thanks for the tip.

I might have resolved the issue myself though.  I just applied another layer of Future and the windows seemed to have cleared up a bit, certainly whilst I was applying it they cleared up.  Although they are still a little misty now the Future is drying, but not as bad as before.  I will see how the layer of Future cures and if need be apply another layer on Saturday.

If all else fails I'll try IPA or go down ye' olde olive oil route.  Applying olive oil worked wonders for my 1/48 Huey when I sprayed it with Humbrol rattle can matt varnish and that frosted, although I don't really like the greasy layer it left behind but I did over do it a little.

Oh well I live and learn, I thought I was safe using an airbrush for matt varnish but I think from now on I'll apply matt varnish by hand, especially where I can't (or have forgotten to) mask clear parts!

Vallejo Model Air is acrylic, right?  I've never used it but it seems like most acrylic paints can be removed with isopropyl alcohol.  

I recommend trying this:  dip a small brush in some 90% isopropyl alcohol and gently start brushing away the matte coat.  Don't use a soaked brush but just dampen it.  Dip the brush in the alcohol and then touch it to a paper towel.  Be careful not to brush any of the surrounding color off.  This may take a while but it may work.

After you remove the matte coat it may be necessary to brush on a clear coat like Future or Humbrol clear to restore the shine and clarity.