Ask-a-Dave's-Gardener: Plant Emergency! Mango Plant rusting away, 2 by snowdoggie

snowdoggie wrote:
Greetings Gardeners,
I have 2 mangos indoors in a bright big windowed room in San Francisco, CA
They were doing fine until we moved offices and then I noticed the leaves were turning brown, first it was just a leaf at a time, then more and more. The leaves would then just drop off the plant.
Also after we moved we discovered some small bugs on it as well, it looks like small white/clear bugs that turn black as they age. The rusting started around the same time, I have sprayed it with insecticidal soap which was not that effective and changed to Bayer Insect, Disease, & Mite control 3in1. But it has not resolve itself. Most of the leaves have already fallen off one and the other has most of its remaining leaves rusted.

Thanks in advance for your help