Barclays US Credit Cards review: Drop in credit limit

I have been a customer for many years and because of one simple clerical error this bank dropped my credit limit to what I owe. I have always paid on time and more than the minimum amount. For you to drop my limit for one simple mistake is ridiculous. This is not how good customers should be treated. To rectify this all you have to do is reinstate my prior limit.
This card is used by me for cruising with carnival cruise line. I am scheduled for a cruise in February and will not be able to use this card because of your actions. I will be notifying Carnival about this action because they are the ones who suggested this card.
Thank you in advance for your assistance.