My windscreen wipers judder?

Before taking the car to be serviced today, the wipers worked perfectly. As soon as I drove out from the Citroen service dept, the wipers judder, what shall I do, Citroen say I must have new wipers, but they worked until the service, can I put washing up liquid on to the wipers or windscreen wash liquid. The Berlingo is only just 2 years old.