[Your address and contact number]
[Reference: order number]
On [date], I bought/placed the above order with you for [item]. The [item] has still not been delivered.
We agreed at the point that I placed the order that it would arrive [on date / within timeframe].
Under the Consumer Rights Act you are required to deliver the [item] to me at the agreed time. As I have still not received [item] and it is past the agreed time, I believe you’re in breach of contract.
In accordance with the Consumer Rights Act I am giving you a final opportunity to deliver the goods.
[Explain why you need the item promptly.]
If you do not deliver the [item] by [date], I will be entitled to consider our contract at an end and will expect you to refund me the full purchase price of [£xx].