Thanks for bringing up T-Force. I'd suggest that people reach out to them via Facebook or Twitter if they need help. They are quite helpful and friendly especially when you've had no luck with 611.
Although they don't really reply your message immediately (there could be a 10-20 minutes delay), they seem to be able to actually solve your problems, and unlike when calling 611, you can just leave the chat window open and do your own thing as you wait for their response.
Not specifically the My T-Mobile issue in my case though, to be honest. With all this fuss I decided to leave T-Mobile and port out my number. But, I didn't know my account number, and obviously I didn't really know where to look. First 611 told it was my phone number (as with most prepaid customers), but my new carrier insisted that was not the case. Tried to call 611 again but the line was busy and I didn't have all day. I figured, after seeing Amanda's reply, that I should try T-Force. And they helped me find the correct account number and I was able to finish the port-out process.