Servicing your boiler the truth
If your boiler has not been serviced in years, servicing can be counter productive. Opening up the heat exchanger and valves can cause leaks and sometimes it may only be the scale that is present that is preventing leakage. This will mean renewing all gaskets, washers etc, just to ensure it returns to being water tight (not to mention the extra cost on materials and added labour).
If your boiler is still in a warranty period, the T’s & C’s will state that you need an annual service, so have it carried out (you may have to ensure that the Gas Safe engineer you use, is accredited with the manufacturer).
If your boiler is 10+ years old and has not been serviced for several years, then i would suggest that you react to any issues and do not service.