If the collar is a Lupine brand, they should stand by their guarantee. Just take it back to the store.
Whatever you do, please don't get a chain collar! That could be very dangerous. They could catch their teeth or jaws in it while playing, with nasty consequences.
There's a spray or gel product you can get at some pet stores called Fooey! that is just about the nastiest stuff out there - it's very
far more so than bitter apple spray. You might want to give that a try.
If you do, though, make sure you wash your hands very thoroughly, or you'll end up tasting it too. I've used it on our garden hose to keep the dogs from chewing on it, and it worked wonderfully - one lick & they never touched it again!