Officially, there is no way to replace a band on a Fitbit Charge or Charge HR. Unofficially, here's how you do it:
You'll have to buy a replacement band for a Garmin Vivofit. Search eBay and you can get one from China for $1. Or if you just can't wait and you're willing to pay more, you can buy them on Amazon:
US: http://amzn.to/2c1qATJ
UK: http://amzn.to/2e27dzS
Canada: http://amzn.to/2c893wu
Optionally, you can also get a "Fitbit Charge Cover" to go over top. Search eBay for one cheap from China, or Amazon:
US: http://amzn.to/2bSE2zd
UK: http://amzn.to/2dAPWOM
Canada: http://amzn.to/2c89Qh7
And here's a video of how to put it all together:
