Well, if it makes you feel better, you're not making any progress because your pet store has misinformed you on how to tame budgies
The stickies linked above should help to straighten out your methods!
Basically, the talking to them calmly is a great first step, and you should do this for a long time until they aren't anxious anymore when you're near their cage. It seems you're already through this stage, so you can get to the next one:
You can open the cage door, and put your hand in, but DO NOT try and make them hop on! That only terrifies them more and tries to coerce them into something they aren't ready for yet.
Put your hand as far away as possible from them and talk to them reassuringly. Do this a few times a day for as long as it takes to realise your hand isn't a threat. They will be active and ignore your hand, or will be curious about it. Both are good!
Once they're comfortable with it in that place, move it to a new place, slightly closer than they are. Same steps repeated here.
Eventually, once you can put your hand near enough to them, you can offer them millet or seeds from your hand and see if they'll eat it. Once they're comfortable with that, you can offer them millet held in your hand while you extend your pointer finger, and then see if they will hop on. Don't force them, though--hold it out just enough so they have to stretch for the millet, and eventually they'll realise that it's a great place to stand!
This is just the beginning of building trust
Yes, it is harder to tame four budgies at once, but once one of them is willing to step up for seed or millet, the others will follow suit.