Sounds like it is time to visit your local quality independent bike shop. I am assuming that the left side lockring is off and you cannot remove the bb cups at all. Try soaking the oustide with a rust remover first. There are Park and Var tools made to remove very stubborn bb cups. The average Park bb tool will not do it in this case. If the left side bb cup has a series of 6 or so holes in it, a pin spanner should be able to do it. If it has narrow flats toward the spindle, that gets more problematic. Pay the bike shop to get this done.