I hear you... I don't know what the Vostro 3500 looks like inside. Check your Repair manual (it should be online). If your BT is user replaceable, the info will be there. My laptop is 8 years old and I am not ready to shell out $3500 - 4000 to replace it with what I would like to have. I invested about $20 for the card on eBay and downloaded the drivers from Intel. It was really a no-brainer install/upgrade. I did some additional upgrades to my system and now it runs better than new.
If your laptop was not included in dell's W10 testing, you may be out of luck trying to find a driver that will solve your issue
Well, I hope your BT is not MB integrated.