CBSA officers are generally nice people and do try to be helpful. But the shxt storms start when they have mis-communications going on and are too busy to reply your calls / emails. If you have the option to, show up at their office and demand to meet the officer dealing in your case. That always worked for me.
Ever since the change from "Customs" to "CBSA" their customer service level has increased dramatically. That's what I found.