No sound on my Sony Bluetooth Headset because Windows 7 can't find Bluetooth peripheral device driver

SO, I am dealing this problem for the second day in a row and no working solution still. I own the latest iMac 2014 (though the model is exactly as 2013) 2,7 Ghz with Bluetooth 4.0, I've installed through Bootcamp Windows 7 x64. My bluetooth headset Sony DR-BTN200 http://store.sony.com/bluetooth-headphones-zid27-DRBTN200//cat-27-catid-All-Home -Theater-Headphones (which is on Bluetooth 3.0 and of 2013 year model) is working fine with Mavericks and Yosemite on my MBP, but not working as it should on iMac with Windows 7..

THE PROBLEM: I find the headset, connect it, but afterwards Windows writes that no drivers for Bluetooth peripheral device were found (3 or 4 encriptions like this, so, 3-4 drivers needed). The headset itself guarrantees fine working with Windows 8, the producer doesn't give any drivers to install, you won't find them on Sony's website - it should work as plug-n-play, they say those drivers are preinstalled on Windows 8.

WHAT I'VE TRIED: So, the problem, as I've read from many-many-many sources is common for everybody running Windows on Mac devices. In cases with notebooks it is easy to solve (if you know it) - download the Bluetooth software from Broadcom (the producer of Bluetooth adapters/receivers of Macs) http://www.broadcom.com/support/bluetooth/update.php - install, it finds the devices and istalls correct driver. This worked with my MacBook Pro 2010, on iMac it stucks on recognizing devices - nothing happens next, like it doesn't recognize any bluetooth device. Downloading many other drivers packages didn't help either, nor Toshiba Bluetooth helpers could detect Bluetooth headset to properly download the correct drivers (though it was already recognized by Windows, just couldn't connect properly), nor different other programs like Bluesoleil, Blue manager and so on.

On other notebooks and computers many try to install manually the drivers, usualy Microsoft Windows mobile-based device support. I've tried to install many drivers, all of the Broadcom drivers I've found (including the Broadcom Bluetooth 3.0 USB driver that makes the headset work on MBP), and I must say that Windows recognizes (doesnt show the yellow triangle next to the icon of the driver) only for the Microsoft Windows mobile-based device support driver. Though it's like that, the sound still is not playing out of my headset. On MBP after the drivers were installed, I chose the device in Printers and devices and there was an option of Control (maybe I remember the name wrong), it went first in the right-click menu, and aftewards there was a page were I could connect my headset through ticks/checks on different options. Nothing like this appears if I install any of the drivers on iMac (nor Broadcom, nor Win mobile-based). I must also mention, that some kind of package that I've downloaded from Toshiba or Acer's Broadcom Bluetooth kit, I don't remember, installed some bluetooth drivers (Bluetooth Audio, "receiver" if I recall it correctly and 2 more), that were recognized as right drivers for peripheral device when I connected my headset, but even then - no sound came out of the headset.

HELP ME: What shoud I do? I've tried all of the methods that are on the net. Sony store won't help me out, because the problem is not in the device - it's in the software/hardware of "your iMac". The headset works with Mac OS, should work fine with fully-Windows PCs, it just doesn't with iMacs on Bootcamp Windows. The interesting thing is that updating windows to Windows 8 might also not help, since Sony guarrantees only work on pre-shipped with Win 8 devices, not with the upgraded devices. I do think the problem is with drivers, that Mac's Bootcamp utility doesn't come with pre-installed Bluetooth drivers for connecting Bluetooth headsets, only for the Apple mouse and keyboard. I must also mention that I've tried to install manually many of the Broadcom drivers, all of which were for Bluetooth 3.0 or 4.0, they didn't help.

It's awfull that I've got the latest iMac, so the latest hardware and face such problems. I only think that a cheap 5-7$ bluetooth-usb adapter could help, maybe it could recognize the headset and therefor install its own drivers for its manufacturer. But I don't imagine how would it work and connect since iMac has a peinstalled Bluetooth receiver. Is there a software sollution? An app or driver?