It's unusual to have manganese toxicity when the pH and calcium are that high. Manganese toxicity is usually a problem in acidic soils, thus the remedy is typically applying lime, which would not seem to be a good idea in your case! Nor would applying anything that lowers the soil pH because that would make the Mn more available.
Do you know if that measurement was total manganese or extractable manganese?
I think because this is an unusual problem my advice would be to ask your local extension office for advice, or contact the lab for their recommendations.
