Data released under the Official Information Act shows the average wait time for the first initial contact, by phone, is 11 days, but 35 days for face-to-face contact.
That compares with a four-day average wait time for adults to receive a first contact and six days for face-to-face contact.
"They just haven't got the number of staff they need, that's the problem. If only we had more staff, we might be able to do more visits," she said.
The CDHB says approximately 81 per cent of all young people referred to the specialist mental health Child and Adolescent Service (CAF) received their first initial contact within three days.
More than half of those referred were seen within eight days.
"It is a long-term problem because the root of it is a lack of training and investment into training for the last 20 years," Bagshaw said.
"It's ridiculous at the moment, in terms of clinical psychology output, there's only six in Canterbury a year - we need 60 a year.
"And it's not because people don't want to get through, there's loads of psychology students, tons of them, but the clinical area for training is very, very limited."
Children and youth are not necessarily more complex to treat but they are constantly changing, she said.
"The way you can communicate with them needs to change over time because the way they understand also changes all the time.
"Professionals need to learn to keep up and listen much more intently to their patients."
Canterbury has had a lot of success in terms of encouraging those who are struggling to open up.
"We're saying all the time find someone to talk to, find someone to talk to and then there's no one to talk to."
Increased demand at CDHB child mental health service
General manager specialist mental health services Greg Hamilton said the CAF service continues to experience significant demand which has grown over recent years.
5197 children and young people have been referred over the past 12 months - including 553 in March 2021alone.
"Staff have worked hard to respond to the increase in demand, however the average wait time for non-urgent cases has increased," Hamilton said.
All referrals to the CDHB child and youth mental health services undergo a same-day triage and contact is then based on urgency or the type of care required.
Hamilton said awaiting further information can be a contributing factor to a delay in someone receiving face-to-face contact from the CAF team.
"However, those waiting for non-urgent treatment are contacted regularly by a clinician, and the consumer and their family have our contact details if their situation changes or their needs become more urgent.
"Reducing wait times for the CAF service is a priority and specialist mental health services is constantly looking to strengthen service delivery, and our use of resources in order to ensure we are can respond to the needs of our community."
