Clutch and smell

My friend had her clutch replaced two weeks ago costing £600 but there is still a strong smell of burning rubber when she drives and the clutch feels spongy and has dropped near to the floor. The garage says the smells are from the residue of the old clutch. Are the fumes toxic and what is their explanation feasible plus why is the new clutch so low? She has no way of telling if they have replaced the clutch with a new one, if they have done their job effectively or if she is at risk.