The leaves on my holly bush has black spots leaves are falling also ant are on the stems

Are there greenfly on there as well? Sound a bit like sooty mould

Ants on the tree indicate the presence of aphid infestation or scale infestation, possibly both. Check the stems, branches, backs of leaves, and new leaf growth for evidence of either/both, and treat accordingly to remove the infestation, at which point the ants will disappear. Black spots might be leaf spot, but the infestation of whatever is the thing you can treat.

Holly trees shed their leaves at this time of the year, mine go yellow with spots on before they lose the old leaves.