Corgi engineers?

Just had a new boiler installed at my father in laws house and the engineers haven't done a great job. Original quote was 1900 to install a new condensing boiler and any ociated pipe work, flush the system, put TRV on all the rads, and replace the old flu. Now there saying after doing the work and the heating not working that the system is old and not efficient, and they need to put 2 two port valves on the system a new pump and a zone pack to bring it up to standard at additional cost of course. shouldn't they have suggested this when they done the inspection prior to giving the quote?. Mon, they bricked up around the old flu, fitted new TRV, Tues, they never turned up, Wed, they fitted the boiler and left without getting the heating to work. today they have gone back to sort the heating out and the up shot is that you can have either the heating on or the hot water but not both together, they left a rad leaking and forgot to put TRV on 2 rads. any advice from time severed plumbers