Return item for refund to retailer, missing in transit - who responsible

brainiack

What are my rights or expectations if I have ordered an item from an online only retailer (UK based), the item is sent and dispatched to me. I return it day after receipt for a refund, using the free returns system (Collect plus, by Yodel), and then the item goes missing and doesn't make it back to the retailer. Do I insist the retailer issues the refund, and they claim from the delivery firm? 

How long should I be expected to wait? The item is over £100 value and I want the refund ASAP. If the delivery return provider loses something on the way then that's not my fault, I did not contract with the delivery provider, only the retailer so are they still responsible for my refund? 

Manxman_in_exile

s34(5) of the Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013 says that you should be paid your refund on whichever is the earlier date of either (a) when the seller gets the goods back, or (b) the consumer supplies to the seller evidence of having sent the goods back.

The Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013 (legislation.gov.uk)

It's not entirely clear to me what would constitute "evidence of having sent the goods back", if the seller were to dispute what you'd actually sent back as opposed to the seller's courier "losing" it.