B & H bad business practice

I returned 2 items at the same time and they sent e-mail acknowledgement on both saying they received them back. One was credited right away and it posted today. The other, worth almost $3,000 is nowhere to be found. I called them today and they said "it's in process". I'm like "no it isn't". I explained about the one item being credited but the other expensive one not. He was like a robot "it's in process". I could get nowhere with him. They say in the mails that it could take up to 3 business days for the refund. It's past that now. Are they in the habit of sitting on people's money (for obvious reasons)? Normally I have not had a problem with getting my money refunded by them. Their customer service really blows! What should I do next, in addition to writing them off for further purchases?

Bill