Many thanks for your patience, it is appreciated. I am now pleased to be able to provide further assistance with your query. First of all, I am sorry to hear about the issues brought up by this. It must be a frustrating situation to be going through.
If they do not deliver the sofa as promised then they will be acting in breach of contract and you will indeed be entitled to your money back. I see you asked what could be classified as ‘never’ and you can’t just wait indefinitely to ensure that they do not deliver it and the law simply places a requirement for delivery to happen either as promised, or within a reasonable period of time.
So if the delays are becoming unreasonable and there is clearly no likelihood of it being delivered any time soon, then you can still rely on that to cancel the order, even if it was bespoke.
Just because it was made to order does not give the seller the right to take as long as they want and not have the obligation to refund you. In the end, an unreasonable delay can still amount to a breach of contract and allow you to cancel.
The issue then is what is unreasonable and when does that apply. Sadly there is no answer to that as each situation will depend on its own facts. For example, some of the delays may have been reasonable and understandable but if they are not taking active steps to overcome these and the delays are now within their control, that is when you can argue that it has become unreasonable and you can cancel for a refund.