should i get my boiler fixed or replaced?

My isar he30 has given me another major leak has caused numerous damage over the last 6 mths, new plaster ceiling, redecoration etc now a plumber tells me i need a new diverter valve (present one leaking)about £100+ labour but has advised me to ditch the boiler and invest in a decent one with a 5year guarentee, it also keeps saying L9 and i dont know why Im a single female with a young family and disabled son i cant afford to throw good money after bad, He says these boilers are cheap and are known in the trade with constant problems, is he right? hate being ripped off what should I do?