Nile Corp. Did not ship all items in my order. Promised to send items later and did not do so. Refusal to refund, credit, or send. City of Industry, California

After a 4-5 year perfect relationship with Nile and over $1150. of orders in the last 14 months alone.Nile has decided to steal $3.90 from me, by not sending the ordered product, refusal to replace after a promise to do so along with a refusal to refund my money either.

 They are of the attitude that it shouldn't bother customers to loose a few dollars to them, here and there.  They also say  they can see inside the box you have ordered and that they know it's there.  It's like being in the twilight zone!

I equate the customer service to speaking to a bag of bricks except for their emphatic denial of EVER making a shipping error.  Prior to this, I had never complained.  Had a missing item several years ago, that I didn't bother to report because it was too much hassle, however I did not hold that against them, as I chose not to call them, to notify them.

 I really needed the product they didn't send this time.  I offered to reorder, if they refunded, in order to save THEM the shipping cost associated with sending me a single item.

My orders range from $70. - $150.  The order total in question was $ 138.  They have decided that they simply do not have to adhere to any credit card processing rules and that it would be worth loosing a customer in order to steal $3.90. 

I am wondering if this is a common practice, now that I have been informed that a fellow jewelry store owner was reduced to tears when alerting them that a jewelry display piece under $2.00 seemed to have a manufacturers defect.  She gave up on getting  a refund or replacement. 

Does it even make sense to loose thousands of dollars of business over $3.90, even if you believed yourself to be correct?  They had never had a complaint or a missing item report prior to this.  Keep in mind, they originally agreed to ship the paper bracelet boxes, then called to tell me they decided not to.

Is the benefit of defrauding a customer of less than  four dollars more lucrative than the customers orders?  Perhaps it is, if you do it often enough.  I believe the truth shall be revealed.