No Feedback for Collection of Incorrect Item

On 20 October I bought 2 sets of the same item via Groupon. Each set was given a separate voucher to distinguish them as part of the delivery process I assume. Both orders were delivered simultaneously but one was completely wrong. I contacted Groupon customer service via their website to request a collection of the incorrect item. I heard nothing back other than the automated email response. I then called their contact centre a week later and was told that I could arrange collection via their website. I duly tried this and got an automated response that due the nature of the order, that it could not be returned. I called Groupon once again and was advised by the call centre agent that he would log a manual collection and send me an email confirmation thereof. He also advised me that unfortunately the item I'd originally ordered was now out of stock and that I would get a refund when the incorrect item had been collected and returned to their warehouse. This was around the 6th November. I have still not had that email confirmation from the agent and nor has the incorrect item been collected.