Answer: It is difficult to identify the bugs you are seeing from your description. I would first want to know that they are pests and not a beneficial or uninvolved third party!
Whiteflies are about 1/8" long and fly off when the plant is disturbed. Aphids can be light colored, pink or yellow/beige and their cast skins look white on the leaf. It sounds like you've used everything in the book on the bugs, some of which should have controlled them.
I would suggest you capture a few and take them to your county Extension Office or a good local nursery for identification. With a good I.D., a proper control can be suggested, if needed. If you'd like you can submit another question with a detailed description and I'd be happy to try to identify the pest.
Finally, remember that just because it is a pest, it does not necessarily need controlling. Damage must be significant to justify control efforts and the crop at risk should have plenty of productive life ahead.
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