bird feeder, what sort do I need?

The problem I have is that birds don't seem to want to eat mixed seeds feed. I've tried two types, with ingredients of heat, kibbled maize, red dari, black sunflowers, kibbled peanuts, pinhead oatmeal, flaked naked oats. The target audience is listed as robin, greenfinch, house sparrow, chaffinch, great tit, sisikin, and all of these birds frequent the garden.
One issue might be the perch feeders; perhaps the birds that like this food prefer a platform or table of some sort?
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I feed a no mess mix and all the birds use it - robins, all the tit family, starlings, wood pigeons, dunnocks, bullfinches, blackbirds and especially the sparrows. I also feed sunflower hearts separately.
I feed in two cages [off the ground] for the small birds, a ground feeding tray, and I also chuck some in among shrubs for blackies etc to access.
The cages have bases, so even birds which are ground feeders [dunnocks, chaffinches etc] can use them. The robins learnt to perch very quickly.
Try as I might we can't get the blackbirds to come to the feeders and I've only ever seen one loan goldfinch. No sunflower hearts here nor nyger seed but they have, at last, started selling naked fat balls so I don't need to spend time removing those nasty little nets.
I don't do loose seed in hanging feeders and we have no grey squirrels here so no need for special cages to protect feeders for smaller birds.
The birds get a 250ml scoop per day of mixed seed on the ground which means there's none left for rodents and one of our dogs is a demon ratter anyway.