Sounds to me as if it was overtightened the last time the oil was changed making it difficult to het off this time. Threads have been stripped and it won't tighten. The bad guy is who changed.the oil the last time.They said it was seized but managed to get it off. When they tried to screw up the bolt it just kept spinning, So needs a whole new sump.
Well it would be my word against theirs, I can't argue with them as I have no proof. I could be the metal expanding with the hot and cold.