Mine usually both have Milbemaxwith no problem, at about £4.50 a pop. Our vet recently gave Millie Panacur instead as a one-off because her bum was playing up a bit.
He was a bit concerned she had ingested giardia (sp?) from drinking from the becks and, with a lot of rats around the farmyards, there was a fair chance of water-borne parasites. Apparently, it's the only one that zaps them all. Dunno if that's right but it's worked. But we'll be back to Milbemax next time because what it did to her rear end initially was enough to put me off breakfast for a week.