I've never had a problem getting the upgrade fee waived either. I've always done it in chat and it has only taken me one try each time.
I simply state that I have been a customer for over ten years and have never once paid my bill late. They usually take a few minutes to review my account and come back to tell me that the credit will be on my next billing statement.
However, from what I've read, it may be a little more difficult to get them to budge on it this time around. It's worth a shot though.
Either way, $40 will certainly not get me to switch to NEXT with a single line account that has unlimited data.