my new boiler smells horrible?

the boiler has caused a noxious smell since it was installed last nov. I have called out the firm twice about it, but they say it isn't smelling, but i can smell it and it's causing me headaches and sore throat. The outside pipe has a connecting valve type thing which constantly leaks (only slightly) if you touch it underneath you get oil on your fingers. the make is Worcester Greenstar Heatslave 18/25.
could it be caused by oil being spilled on the components whilst being installed? and if so will it eventually stop smelling, or do i need to have it washed. I would like the boiler replaced really, is that likely?!