If the offence is �either way� (that is it can be heard either at the Magistrates� Court or at the Crown Court), a decision is taken where it should be held.
Usually, the defendant is asked to firstly indicate his plea. If he pleads guilty he stands convicted and the magistrates then have to decide whether their powers of punishment (six month�s custody) are sufficient. If they consider they are not, the defendant is sent to the Crown Court for sentence (note, this is not the same as being committed for trial).
If a not guilty plea is entered, or the defendant withholds his plea the magistrates hear an outline of the offence. If they decide it is too serious for them to deal with they commit the matter to the Crown Court. (This is where �committal papers� have to be prepared as I explained earlier). If they decide to retain jurisdiction the defendant has the final right to a trial by judge and jury. If he opts for Crown Court, then, again, committal papers have to be prepared.
I suspect your ex is involved at this �Not Guilty� or �no plea� part of the process. It seems likley that magistrates have declined jurisiction and an adjournment has been allowed to prepare for committal. I do not understand why the magistrates have refused to accept a plea. Defendants are encouraged to enter their plea at the earliest opportunity.
Note that all of the above applies only to �either way� offences. If the matter is indictable only (that is, it can only be heard at the Crown Court) then the defendant is �sent� to the Crown Court usually on his first appearance before the magistrates. In this case no committal papers are needed.
What was the charge?