Its unusual derek as most birds are eating heartily now to keep warm in this cold weather. It might be worth emptying the feeders and cleaning them out. Dry them well and fill them up again.
If the seed has got particularly wet it might it might have gone a bit rank and not very appetising. There's no reason why the birds shouldn't be loving a feeder of mixed seed every few days at the moment.
Some mixed seed, offered for sale are not that good and often contain cheap ingredients like wheat and crushed dog biscuits, to bulk the weight and volume up
Perhaps you could try experimenting with different foods, like sunflower, peanuts,nyger etc to see what birds can be attracted in your area
I have 2 seed feeders and could fill them twice a day. I'd agree with what Maidup says - empty and clean the feeders and maybe try a different food. I use the no mess stuff as it doesn't contain as much corn as some others.
We have to fill our feeders every 2/3 days and the fat balls disappearbefore you can get indoors! My husband has put a tray under our feeders to catch the seed that the birds pull out and dont eat! We put that onto a different part of the garden, on the ground and other birds eat it!. At the moment it is chaffinch and a mixture of the tit families that are on the feeders here in Devon. Definitely clean out the feeder and restock.
I have had the same problem as I bought some mixed seed which the birds did not touch, so have changed back to sunflower hearts & a new feeder & now the birds have returned. They certainly like the fat balls but do not seem keen on peanuts or niger seeds.
I always find that with new feeders the birds don't come near until the seeds have sprouted, you've thrown them away and put a new batch out. Then they come!