If the drawee bank misses the midnight deadline (and yes, the back of the check would be very important in proving your case,), and you can prove that you suffered a loss as a result of their violation of the UCC, you may be entitled to damages up to the amount of your loss. If they returned the item late, don't expect them to own up to it and hand over the money, you will probably need an attorney.
2nd anon. based on your description, you bank may be trying to cover an overdraft, and going back two weeks is outside the bounds of the UCC as they are clearly outside the midnight deadline. You are covered by
UCC 4-402 which covers "wrongful dishonor"
Your best option is to speak to a manager so they can tell you how what they did is legal. Hopefully they will acknowledge that they should not have done what they did. Also bring in any "returned check fees" you may have incurred from third parties as the statute does provide for damages caused by the dishonor.
Once the dust clears, if paying these items will leave you overdrawn, you will still be responsible to your bank for paying it back.
If your bank refuses to work with you, and the loss is significant enough for you to want to press the issue, again you may need the help of an attorney. Also, you as a consumer always have the right to voice your displeasure by moving your business elsewhere.