I had the same problem with an omega v6 this time last year. The burning smell/smoke was the aux belt burning out. Once it snapped i turned off the engine and went for a beer! Once it had thawed out i filled it with water and it pissed out of every place it could. what was bought as a cheap car to sell on had too be sold as a non runner for a loss, as the engine needed a full strip down.
As said above, the garage has fooked up big time, and should recover your car and repair it, no question.