The RACV website say that the Meridian is one of the more difficult car seats to use (installation wise) compared to other types. This may be the problem, but you will most likely find your car is the problem. Have you tried fitting it in the middle seat? I sell pre-loved car seats as part of my business and I had a customer have the same prob with a Safe N Sound Royale she purchased from me, before she bought it I told her to go to Baby Bunting and try out other types first in case they fit better, but none of them did so she still went for the Royale. You will find it will fit better when it is forward facing, but probably not much help to you at this point in time! The Royale customer only uses it in her car during the week, then moves it into her DH's car on weekends. The Compaq model is narrower than all the others, but you may still have problems with it when it is rearward facing.