head assembly for McCulloch cabrio 321?

where can i get a complete head assembly for above strimmer. A neighbour recently cut down my garden and mangled the gearing on his cabrio 321. He is trying to sting me for £90. I could probably purchase a brand new unit for less than that. Alternativelly could the gearing be repaired. I have no technical knowledge which my kind neighbour is using to his avantage. As far as I know it is the bit between the long shaft and the cutting head