Look up your state's debt collection act (federal act only applies to third party debt collectors). Odds are pretty good that Cap One is violating something. The people who manage collections at the big lenders are just $12 an hour drones working in call center operations. If you can document a debt collection act violation, you will have some leverage to keep Cap One at bay or even get a nice settlement check if you can get a plaintiff's lawyer interested.
In most states you can tell a debt collector that you do not want to receive any more debt collection calls. If they do not stop, they have violated the act and can face civil penalties. Also, in most states you can request verification of the debt in writing and there are consequences if the creditor doesn't provide it. Most big lenders will screw that up. There is also a long list of debt collection tactics that creditors cannot do (threaten criminal prosecution, call employer/friends/family, excessive calls). Study those and document anytime they cross the line.
It is also a good idea to send in a written request for forbearance. Cap One will never do it. But in a subsequent lawsuit, the jury will hate on them for not being reasonable.
Finally, watch out for the repo man. Park in a locked garage or have a friend block your vehicle in wherever you park at home. If you see the repo man trying to take you car, go out and yell and scream, sit on the hood of the vehicle, make a scene. The repo man has to stop if there is a breach of the peace. If they don't, it is a wrongful repossession and Cap One will be liable. Be sure to video. Of course, you cannot put your hands on the repo man. Understand that he is just trying to make a buck and is just a cog in the big machine.
If they repo your vehicle, you still have the right of redemption. Cap One should be obligated to send you a notice of redemption and sale (depends on state law and the contract). Even if they don't do it, you should send them a letter asking to redeem even if you can't pay off the loan. That may gum up the process and give you leverage if there are debt collection violations.