I did customer support by phone and then was switched to an e-mail support team. Yes, it is stressful dealing wth unhappy people that tend to take it out on you. The first weeks of gaining confidence in what I was doing were the toughest.

If there is an option to switch over to e-mail team in a reasonable amount of time, having done both, I found that the better option. It seems to be a calmer method of communication. An annoyed e-mail didn't bother me as much as someone yelling on the phone. Plus, you have more of a chance to look up an answer to a doubt you might have and prepare a clear response.

I hope things get better for you.