I'm loathe to give up on plants. Assuming, they are in the ground, I would feed them as advised by the RHS until the foliage has died down, then dig them up and let them dry. Give them one last chance next year, perhaps in pots. If they still don't perform then they can go in the compost. Maybe the package exaggerated the vibrancy of the colour or maybe you dont have what's advertised. I'm sure that happens in mass production and packaging.
I have to say that it's been an odd bulb season for me this year. Daffs have come up blind or not at all though planted to sufficient depth. In one circular rose bed which is ringed with a mass of daffs and has been for 40 years, only one half has come up this year. No leaves at all, let alone flowers. The roses look poorly too. Hard to say if there is disease of this is a result of last year's very hot dry summer and the very wet winter. Needs investigating.
More than one person has told me their daffs have come up blind this year, again though planted to sufficient depth.
I bought various tulips from T&M last year, didn't get them in until Nov but they look very promising. Healthy leaves and fat flower buds developing.