I've heard that their support system is overwhelmed and response times are ridiculous. Call them at a time when you can sit on hold for as long as it takes. Just put it on speaker and answer some other emails. Once you get someone on the phone they usually can resolve things quickly.
If your XML uploads are freezing, that's likely a network issue. Try doing it from home instead, or from Starbucks.
I feel your pain on this. Good luck!