It's time for you to speak with Top Management to check why the frequent delays. If it's a one off thing perhaps it's because there was a tie-up with cash flow but if it happens all the time, there's definitely an issue.

You should weigh the consequences of bailing out before something drastic happens, or do you think there's a possibility of things improving in the near future? If so, you may just want to persevere - loyalty does pay