Land Rover Range Rover non start

Bought from auction 6 months ago, battery was flat had mechanic attend with diagnostic equipment, he read all codes put it to standard and off she went good as gold for some time. Had a misfuel problem, was immediatly drained, new f/filter re checked and programmed, all okay. Six weeks later, Christmas morning she refused to start first thing. Twice since she has started on her own first thing. Otherwise she is an addict for a sniff! Mechanic has found two injectors leaking back ? Also says needs 6 new heater plugs ? Any thoughts or do l go with the prognosis and cross my fingers. Miles are 77000. Previous owner said she had nothing but starting troubles, had new starter fitted, new battery , 3 injectors , alternator, dash board [?] some wiring loom [?] gave up, sold car [auction] Any suggestions ideas.