I'm having similar issues with the short battery life. The last time I charged, I only used the phone for a short time and the next morning I get a warning saying I was below 15% battery. I tried to kill background activity as much as I could, but isn't helping.
The OE battery is overheating badly and emanating a smell. This exact thing happened with a T-Mobile phone years ago and the problem wasn't present when I returned it for a second phone.
Is it possible to contact VM for an exchange instead of the retailer where it was purchased or is there a risk of receiving a refurb? If I returned mine to the online retailer, by the time I got it back I would be out a phone for at least a week. I suppose I could get a second one and later return the first one.