Your going to get lots of somewhat emotional answers to that question!
I've had mixed experiences contacting PSI via e-mail. On one occasion, I had entered an order (on line) and later realized that I had made an error. I sent them an e-mail asking that they make a correction, and when the order arrived, I found that they had received my message and acted on it even though they never replied to my message. On another occasion, I asked a question by e-mail, and while I got an answer, I couldn't understand it. The answer was correct, but the person who answered the question knew too much about the subject, and incorrectly assumed that I knew as much as he did. As a result, the answer was not helpful to me.
So my experience, and everything I have read here, suggests that the best way to contact them is by telephone.
But I understand the issue with telephone expense. Are you calling about an order? Or are you calling with a technical question? If you are calling about a technical question, you might try posing it here - surely there are folks here who could help you.