Go back to the garage! Make them fix their screw-up. Timing belt job was done improperly.
Plus, you should do the valve clearance check/adjustment while "you" are there.
By coincidence, the ignition system might be faulty (coil, cables, sparkplugs). Or the fuel (injectors).
Most mechanics are incompetent. They are not able to handle simple Fiats with FIRE family engines.
All they can do is VW TDI all day long. Nothing else.