Fuel & thick smoke emmision!

Please, advise me on what next to do about my Landrover "Freelander" V6, 1999 model.

i took it to the mechanic's workshop to stop some oil leaks from my engine, he had to change my cam shaft oil seals, after which he also changed my airflow meter.

now upon taking back my car, I noticed that the engine is not steaming well, it emits drops of Fuel and a thick white smoke while driving!

Please, what could be the cause and solution to this situation.