I orderd a rather expensive backpack from a mail order company specializing in "tactical" gear.  I paid with my Discover card for the cash back, every little bit helps.  Today i received my MasterCard statement and found they billed my MasterCard that they apparently have on file from prior orders.

this is not the first time i have had problems ordering from this company. In the past i have experianced poor comunication during the sale, extended back orders, and being billed for items that were cancelled and shipped weeks or months after being cancelled.

What are my options?

I've gone through the same thing with a few gear distributors on-line... you are more generous than I!  After someone messes me over (like you state this company has done to you more than once) that's the last time I deal with them.  So far, Lightfighter is the only large company that I have dealt with that has been at least 100% on every transaction.  I'm still waiting on another distributor for an "in-stock" package that I ordered almost two months ago and paid UPS 2nd Day Air for shipping.  They charged my card the day of the order.

I show more forgiveness to the smaller dealers here on the board.  These smaller dealers are usually one or two man operations doing their best to bring us the latest and greatest products, usually at a great price!  But for a large operation to drop the ball just shows lack of competency and efficiency.  Both of these deficiencies get passed on to their customers.

Why continue to subject yourself to this company?  Find someone that can get it right.  Post here what you are looking for, and I guarantee that you will find at least two distributors to choose from (and people sharing their experiences with those distributors).  The customer is usually right!  Businesses are worthless without customers, we should be treated as such.  OK, I'll stop now.

-Randy

You could call them explain he situation, have them update your records to show your discover card or take your cards off their file so in the future this will not happen again. I am sure they will credit your MC and charge your Discover card. I do not see this as a very big deal unless they do not try to work with you.  It does help if you printed your order confirmation page that may show which card you used for your order. Then if they give you a hard time you can show them where the mistake was made. If they care about your business they will work with you.

I know the owners are good people, and they are going through growing pains. The really do underestimate the frustration they cause their customers when every single order has some stupid mistake though.

Never happened to me.
I would request a credit on the master card then a charge on the Discover. It should be pretty fast and painless for them.