Last yr a neighbour of a customer came out and asked me to clean upstairs as his window cleaner was a little clumsy and he didnt want him standing on roof tiles to get to most of his windows. As it was where i was working (im in that areas for 2 n half days working) i agreed. Charged him £8 for 3 windows, which was more than the normal chap charged for downstairs plus conservatory. Sorry to the other chap, but in the end the client was impressed with system and got me to clean whole property and im still cleaning it for a very good price.
So for your question, if it was in my areas and price structure in south yorkshire i would say NO if its not near my usual work. On the other hand if it is close to my work, for the inconvenience for just those 3 dormers and frames i would charge either £7 each as they are minging, so £21 if its regular. If its a one off, tell them can have that looking good for £30.