Hey Good Morning,
I was in kind of a similar situation, I had sent my brother's passport for renewal on April 13. The form I filled was "Adult simplified Renewal form" but the previous passport he had was a child passport, so essentially he is considered an Adult now if the age is 16 or over.
The mistake I made was I filled the wrong form and instead I should have applied for a "New" adult passport for him.
His application with wrong form was received by Passport Program on April 13, All of April and May had passed and I didn't see CC charged and after first week of June passed I decided to call to get an update and that is when I found out that I had submitted the application with wrong form, they told me that his application would be sent back with all the documents.
The documents that were sent back, there was also a rejection form which was dated June 6th so I guess this is when they rejected the application.
All documents were received by Canadapost on June 15th.
I will now have to go to Passport Service in person with his new adult form because we are travelling Aug 1st.
I would suggest to try calling Passport service helpline at 8:30AM EST when it opens up. You will have to be persistent, I had luck getting through between 8:30AM EST - 9:30AM EST.
Good Luck!