Additional costs dealing with defective 64GB cards, please advise on a fair resolution?

I purchased an Ultra 64GB microSDXC class10 back in December and immediately encountered read and write problems.

During my first attempt to use card I tried to transfer a bunch of files onto the card using a card reader but within the first few seconds the transfer was interrupted as the card kept disconnecting itself from the computer. When i tried to connect the card it found errors and other times it would completely fail to appear. When i tried to remove the files that were corrupted due to the transfer interruption i found that the delete option was no longer available in the right click menu.

I spoke to customer support who ran me through a series of tests before advising me to purchase another card reader to test it on. So I went out and bought a Lexar card reader which supports SDXC, but this failed to make any difference to the problem.

When all else failed I decided to return the 64GB card back to the store. I took both my card readers to prove to them I had tried several options to fix it. They tested the card on their computer before determining it was faulty and agreed to replace it. But in the process they left my card reader cable behind on their computer and I too forgot about it until it was lost and too late.

 A month later when i received the replacement card I put that in to the card reader and guess what…yes folks that too was also defective.:cry:

This time instead of returning it to the store again and risking another month of waiting I decided to return it to Sandisk but I was sent an email with a USA address advising me to send it from Australia to the USA at my own cost. By this time I was frustrated that almost 3 months had passed, my initial defective card was replaced with another defective card, I had incurred the cost of several international calls made to Sandisk, i had purchased a second card reader which made no difference and then lost my card reader cable at the store and now i was looking at sending my card to the USA at further expense and I was told after all the time and trouble i had gone through that I may only receive a class 6 card as opposed to the class 10 I had payed money for.

This to me did not sound fair. As a customer all i did wrong was to purchase a 64 GB card that turned out to be faulty, not once but twice and it made no sense that I was expected to cover the costs of trying to resolve this problem at my own expense.

So i proposed to Sandisk that once I send them my defective card that they send me one of their own card readers at no cost to compensate me for the second card reader that i was advised to purchase and for all the inconvenience i had gone through since December. I felt that it was a fair proposal but they refused.

It has taken so long trying to deal with Sandisk support to achieve a fair resolution that i may have now compromised my chances of returning the defective item back to the place of purchase as covered by their return policy. What would you guys advise I do now and do you think my request was unfair?