radio / cd ,interference

hi all , i am having problems with very annoying interference from the radio / cd in my range rover 4.6 v8 with thor engine 2000 model . the noise sounds like high pitched static with variable noises , wether the engine is running or not ,this has been going on for about three weeks . in the last 2/3 days it has now started to be intermittent ???? it has recently been fully serviced and has had new coil and leads fitted so i dont think it is related to them , i am wondering if the amp is causing this ?? or possible where the amp is situated if theres any dampness ?? any help and advice would be really appreciated. if anybody has any suggestions as to what to check and then i can rule things out one by one ..

mozz have a look under the rear shelf, at the box by your rf box. make sure all the wires are on..

hi j the range, i have checked the ones on the right (as im lookin in from the tailgate ) wich i think is the alarm control box . havent had the left side out yet . is the amp in there ? and how does it come apart ? i presume i lift the top cover off , does the side panel open where the cd player is located ? and then what do i check . cheers j sorry my knowledge is **** as i have only bought it 6 weeks ago but everything else works ok and is adream to drive ,my last 3 cars over 15 yrs have been pajero lwb all were great but the rr is a class on its own and a joy to drive many thanks manchester mozz

tis under the drivers side top pannel, easy to remove. you amp will be on pass side behind the side pannel. you will have to push your seats down to get at both of them..