Takealot diffusers

We have bought, so far 11 items from takealot, and have had to return 8 of all the 11 items, because they were faulty and or defective. I had bought two diffusers, after about a week of use i discovered surface cracks on the exteriors of both diffusers ,and on one of the diffusers the surface cracks were so bad that part of the surface had chipped off. These items were properly cared for, and used carefully, I can't understand why, even after caring for them so much, these diffusers cracked. I returned them back to takealot, and was told i would get a credit and or and refund for both items. After 2 days I called them, regarding the return, they told me that they had credited my takealot account for both items, when actually only one of the items had been credited for. The one was credited for and the other was declined a credit, They had categorized this return as misuse. This was not the case, I had used the item carefully, and the cracks in these items were qualitative defects. Now I feel as though I have wasted my money. The other thing is that when you return your items, you do not get credit for the delivery, and then have to pay for delivery all over again, what a waste of money! I am not very impressed!