Are the current posts in concrete or not?
If not...... you could knock in standard square fenceposts (5ft6, £3-£5) right next to the existing posts, and screw the two together using decent screws (or bolts)
Should last 10years
If not...... you could knock in standard square fenceposts (5ft6, £3-£5) right next to the existing posts, and screw the two together using decent screws (or bolts)
Should last 10years