I have had the same problem. FitBit will replace your device up to the one year warranty....after that, the best they can offer is the 25% discount. It is inconvenient that it doesn't hold up better, but in my experience, the replacements I received made the purchase worth it.
But, to sort of help with this problem, I have found that secondary band covers like the one linked below works. It helps prevent that pulling because there is less pressure on the screws holding it together, and it covers the breakage when it does happen. Not ideal, but it's fairly cheap and does help. This is the one I have for my Charge HR.
http://www.amazon.com/Sister-Fitbit-Charge-Designer-Sleeve/dp/B01BLY3SDO