rear suspention woes

Hi all am in need of some help we have a 1999 megane scenic it's just passed mot 2 weeks ago cost £250 to get through. Anyway yesterday I was driving back from work and the was a loudish bang like a stone been thrown at the car so parked the car up at work no problems went to go home an noticed the rear of the car is right down like it's carrying a full load I nursed the car home got jacks out and checked shocks all ok as they are brand new looked at torsion bars all seem ok. Can anyone give me any ideas what has happened and how it could be fixed as I'm stumped thankyou for taking the time to read

rear suspention woes