S.D.
Hi T., Congratulations on your pregnancy!
I also have a mullerian anomaly but it is a different variation than yours. I help moderate a yahoo group dedicated to the topic of mullerian anomalies so I know quite a bit about the topic but I am NOT a Dr. The most common pregnancy complication for ladies with BU is breech presentation. Attempts to turn the baby often are unsuccessful among ladies with BU due to the shape of the uterus. There is some risk involved in the procedure as well--particularly if the baby's head is stuck in one of the horns of your BU. It's very likely that this was the reason why it was so painful when the attempted the version last time. Given your history, I highly recommend going for the c-section. I know that is disappointing but it probably will be less painful and traumatic for both you and your baby.
You are really fortunate to have this variation of anomaly instead of another type since BU has the best prognosis. I have a septate uterus that would not allow me to carry a pregnancy to term (90%+ miscarriage rate!). After many losses I finally had a surgery to remove the septum. BU is the most common variation of mullerian anomaly but many Drs are not familiar with this particular congenital defect and think that BU is the ONLY variation. It sounds like your Dr might fall into that category. I really don't think that a Dr who specialized in mullerian anomalies would attempt the version. I don't mean to say that you don't have a great Dr--just that s/he might not be very familiar with MAs. Even so, you should discuss this carefully with your Dr before making your final decision. Feel free to contact me directly if you would like more info. Good luck!!