"I am given appointments that don't exist"

The cbt therapy available through let's talk for my anxiety and panic disorder is great and has allowed me overcome a lot of barriers I have faced over the past few years. Unfortunately the service fails at admin, I have received 3 incorrect appointments in the past few months making me travel to appointments that have not existed, which is not great for someone who has anxiety about going to appointments. I have turned up at the centre and had nobody on the desk to ask about an appointment so I've had to try and ring the service myself who then tell me appointments don't exist. I have been told I will be called at a certain time and 40 minutes later still waiting, which has a great impact on my day as I can't plan anything around my appointments because I never know if they've actually given me the correct one. For a free service the amount I've spent on travelling to and from the service I could have paid for a few private sessions, which isn't great on a student budget.