"Taming" is actually earning their trust. They are prey animals and we are predators. You need to win over their trust enough that they allow you to join THEIR flock. And Budgie are BIG flock bird in the wild; sometime in the thousands! Keep working with the one that will step up when alone and start teaching her to do it when she is with her flock mate. Mate will see she didn't get eaten for stepping up and eventually will, hopefully, step up a well. Work with them both together for five to ten minutes, then put them in their cage with a treat reward, no matter the outcome of the training. Later, work with them individually for also just five to ten minutes each. If they have favorite treats, stop by their cage often during the day and speak to them, then put a small treat in their treat bowl. This shows them when you appear, good things also appear.
Are your birds named? what kind of cage do they have? A year of slow training will give you fifteen years of love and companionship from these birds.
By the way, Welcome to the Avenue.