BOILER NOISE?

Our Mistral oil combination boiler is causing annoyance to a neighbour 100m away, rural, open field. The chrome flue is vertical, from the roof of a single storey building, on the side of a lane. Looking at the manufacturers info the minimum distances appear to be correct. The main annoyance is noise, the neighbour can also smell oil when walking past the house. Untill this was mentioned I had not noticed the smell and the noise is what I expected from a boiler. The boiler has been running well for 2/3 years, serviced regularly by the heating engineer who supplied and fitted the boiler (corgi registered). I do not want to become a nuisance neighbour, so is it usual for all oil boilers to make some noise. Appreciate any comments on this matter.