The wonderful thing about the "Free Market System" is that you can go to another shop if you wish.
If this LDS is not meeting your needs, then you can go to another one. I realize that in some areas this might be difficult. And although normally I would NOT advocate buying on line... If there is not another LDS within reasonable distance, there is always the internet.
It is unfortunate that you have run into problems with your LDS. Certainly, you should do everything that you can to get your money back, or in some other way resolve this issue to your satisfaction.
Along with satisfactory resolution of the issue, you should probably let the owner know that you are not happy, and why. Also, you might try reminding him that you will share your "opinion" of how this issue was handled, with your friends, family and other divers that you might come in contact with. This is called word of mouth advertising and it can have a huge impact on the LDS.
Granted, not every LDS will be able to completely satisfy every customer.... But from what you are saying, this one isn’t even trying to meet your needs.
I have found that usually, the LDS is the BEST way to go. Sometimes, I guess it just doesn’t work out that way...
But then...This is "just my opinion".