Follow up on broken nail polish bottle

On Monday, I received my order from a certain online retailer (I don't know why I'm still protecting them!) which included a broken bottle of China Glaze Up All Night. Read here for more.
I sent a complaint and 12 photographs as proof within 15 minutes of receipt. The company promises 24- to 48-hour turnaround time for complaints. I heard nothing from them despite a few phone calls, until Wednesday - they promised to give me one-third the amount I paid for the bottle, as store credit. I told them that was unacceptable.
I heard nothing from them again, till today. They've now sent an email asking me to return the "product, packaging and accessories" within 24 hours. So I called up to ask if they meant I should return all items ordered or just the broken bottle and the customer care guy said "I'll let you know in 48 hours." So that means I miss the 24-hour deadline to return the item. Anyway, it's the weekend. How am I going to send it to them tomorrow?
Worse, do they realise this broken bottle has been on my desk, stinking and staining, for five days now? And, I'll get my hands stained all over again if I touch it to repack it.
So much for "customer is king"!
I'm hopping mad. I feel like outing their name. Seriously.
Sorry for the rant. I promise to cool down for the weekend x