Repair or replace?

tiggerbodhi

Our boiler is a 10 year old Baxi Combi (non condensing) recently been playing up, is covered under Southern Electrics insurance for repair, they have been out four times now, replaced the diverter valve in doing this got the circuit board wet and now that is playing up so that now needs replacing, still not convinced after this is replaced the CH will work correctly as even though shows full pressure keeps giving "low pressure or pump fault" this appears to be the pressure switch on the diverter valve not coming far enough out to contact the microswitch for the pump to run.
Once they have replaced the control board the boiler will still not produce consistant hot water, this is due to a clogged secondary heat exchanger (not covered by the SE insurance) quote from SE to replace this and fit a magnafilter is £480+Vat, local trusted plumber is £390 inc Vat.
The question is considering the age is it worth spending the £390 on it to get it back working or putting this £390 towards a nice new condesing boiler that is more efficient in the long run, what is the payback time for an average condensing boiler?
Been told the payback is roughly ten years in gas bills assuming no price rise (quicker if the recent rises are "normal")
Personally being an old school cynic would love my old vented non combi boiler back, 30 years old and could be fixed like my land rover, two different sized hammers and an adjustable spanner!