I actually got a call today from the manager at walmart in regards to my email. He did tell me that I should have gotten the overage and that it was a training issue. He was very apologetic and said that I should not have any more issues. He said if there was a problem I should ask to speak with a manager. He was very nice about it and apologized several times. He said that the overage issue was not an issue because they get it back anyway.
I also asked him about the "review" of the coupon policy. He said that management is concerned about people clearing out the shelves when there is a good sale that can be combined with a coupon. They are thinking that they may have a limit per item like they do when they have a really good sale. Personally I don't mind that because I have gone in before and tried to get an item that I needed only to find the shelves empty.
If you were told only 6 coupons at the wo wm I think you should complain to the head office. They will contact the store and I'm pretty sure the issue will be resolved.