2007 A4 2.0T timing belt issue

Hi everyone, gonna keep a long story short...i own a audi a4 2.0T cab, i had a cambelt kit and water pump changed at 72000 miles about 6 months ago, car broken down yesterday...car starts then cuts out after couple seconds and sounds very rough also cam position sensor has thrown a code up.....
Got the car recovered to an audi specialist, today he's left a voicemail on my phone saying he's taken apart the engine and has found that when the cambelt was changed by other garage the a bolt head has ended up in the bottom of crankshaft drive what does this mean? New engine? I won't know the true extent of damage until monday morning when i go there.... Am i looking at a new engine? Whats the most that could be damaged? i still have warranty on cambelt replacement from previous garage Please advise me thanks. james