annoying noise coming from engine

hi there,

im new on here, but not new to skoda's and vag's. iv had five vw golf gti's, a mk 1, two mk2's, two mk5's and three mk1 octavia vrs, red black and now silver (which is the best colour i think).

over the years iv had the odd minor fault, but nothing serious.....until now!!

i bought my present 2004 octavia vrs back in december, 2 owners, fssh low mileage and well cared for with oil and filter changes every 5000 miles or so.

but two months ago i started to notice a swooshing noise when ticking over, thinking maybe one of the belts???.

so when in for its service i asked the mechanic what he thought it was, and he said auxillary belt??? so when i asked him to sort it while the car was in i thought great thats the only think thats bugging me and if thats sorted brilliant!, however when i picked the car up he told me the noise was still there but not as bad....dont think he had much sleep the night before cos i struggled to notice any difference at all, he then went on to say he couldnt find anything that would cause that noise??? this garage is also a vag specialist so i presume he knows what he's talking about......PLEASE can somebody help me, as the noise is getting that irritating now that im seriously thinking about getting rid!!!!

thanks