> email/ticket based support

This would provide the customer with a written record which could be used against the corporation. Phone is generally favorable to the corporations because the corporation can decide whether/how to retain/destroy records, but the customer will almost never have a transcript or recording to use for their own evidence.

Many corporations have moved to a system where you can either call an automated line which does its best to make you hang up...or you can fill out a browser form which provides the customer no ticket/confirmation number/email/any record that you ever filled it out.