ASK THE EXPERT: What Can I Do When An Online Retailer Refuses To Take Responsibility For Damaged Goods?

Kathy Cartmill from the United States (Yakima) asks:

Online, I purchased futon frame, mattress, and cover. The railings and parts w/it were lost. The 2 boxes had incomplete work, damaged slats. The mattress was 4"; I ordered 6-8". The cover was huge, for a bigger mattress. I reported and sent pics. For 2 weeks I was told nothing, and then I told them I will return for full refund. Then 4 Xs they said they would do one thing or another and never did anything. They told me I had the right mattress and cover. Then when I persisted in asking them to replace damage and missing parts, they said to ship it back. I have all the emails and THEY WANT ME TO PAY OVER $100 IN THEIR SHIPPING COSTS TO SEND IT TO ME. SHIPPING WAS INCLUDED.