If you have an oil boiler you have to have it cleaned! Many ignore their oil boiler just expecting it to run and the service contract you have will take care of it. The results of a plugged boiler will hit you in more ways then one.
Thermostats should be tested for proper operation ensure that their batteries are good and contacts are dust free. There are also other controls that need to be checked at the same time on your boiler that make the contacts to get the whole system operating. This can easily be done at the same time.