Whether 3 phase or not, There would be more problems than what's occurred on
one circuit. You either have one leg of the secondary feeding every other
breaker or in the case of 3 phase, one leg would be supplying every third
breaker. In either case, if the problem were outside the premises or before
the breaker panel/load center, the spike would have effected everything on
every other circuit or every third circuit. I would be very surprised to
hear your power company can't figure out the problem.
At this time they are or should be the best thing you have going for you.
Make sure everyone involved realizes that. I hate to sound like an advocate,
but they have the most experience and hopefully they will feel as my power
company does. Prove the cause to prove they aren't.
Good luck and please keep me informed of your progress.
6469 Old Solomons Island RD
Tracy's Landing MD 20779