Has any service techs been over recently to try & get more heat out of the system?
Could you also post back to advise if the boiler is oil-fired, or gas-fired (is the boiler run by oil or gas).
Do you have a separate gas heater to heat the hot water for the sink and bath, or is this hot tap water obtained from the boiler?
Can you check the gauge on the boiler to tell us what is the psi reading (altitude) (should be 12-15 psi).
Also advise what the temperature needle on the gauge says (should be ~180 degrees when hot).
Can you hear any water gurgling in the pipes, and have you tried to bleed the system.