Phone the planners seriously! if these people are experienced at putting these up they may be know how noisy they are and moved a bit of plan, not being a cynic just understand how peoples minds think. Get the planners out and check the exact postion compared to the application.
You may also consider phoning environmental health or whichever body it is within your local council.
DO NOT SUFFER IN SILENCE!! YOU HAVE RIGHTS! even if planning has been granted, i do not know for fact but perhaps you can argue that thez noise is an unknown quantity, its not like erecting a barn or building an extension, becasue you have definate expectations of the end result.
fingers crossed WP