That's exactly what happened to me. Ex went to miam and got it signed and sent of court papers. I only realised what he done when the court papers dropped through my letterbox.
Ex knows I would have done mediation and avoided courts due to costs and stress.
As frustrating as it is the court case proceeded even though I told courts what had happened. They didn't seem to care, as long as miam signed it and mediation and court fees were paid.
Definitely put detail and information in your position statement about how you had 50/50 for x number of years. Judge will see that and use his/her common sense and not change it to no contact.
At the first hearing the contact usually stays the same as previously until the next hearing. Make sure you keep going back to court to increase contact until its something you're happy with and works for you and your son.