S.,
If you have a dentist who knows what he's doing, you should be able to have a root canal and feel no pain at all during the entire procedure, except, of course, for the sting of the needle when they inject the novacaine to numb you.
Possibly your dentist isn't giving you an adequate amount of novacaine, or isn't injecting it in the correct area.
I have never heard of anyone having twisted root canals in their teeth, and even if there is such a thing, the novacaine is injected into the gum above or below the tooth, not into the root canal itself. I think that was just a cop-out for a dentist who is not very well versed in his field, and obviously doesn't care whether the procedure causes you pain or not. Any competent dentist would stop the procedure immediately if they were causing you that much pain.
Unfortunately, there are some people for whom novacaine just doesn't work, no matter how much they're given, and if that is the case, then there are other numbing agents which can be used instead. If none of the numbing drugs work for you, then there is also the option of being given a sedative to put you to sleep, so that you feel nothing during the procedure, and simply awaken when its all over.
In any case, I would definitely seek follow up care from another dentist, to be sure that the root canals were done properly, since that particular dentist does not sound very knowledgeable about either the procedure itself or about managing pain for his patients.
If you live in New Jersey, near the Trenton area, please send me a private message, and I would be happy to give you the name and number of my dentist, who is excellent! I've had numerous root canals done on my teeth, and have never felt any discomfort at all during any of them!