All good advice. Checked Consumer Protection Act. A defect is significant if a reasonable consumer knowing of it would not buy it. He/she is then entitled to a refund or replacement which is his choice. Repair is only an option if that is not the case. Further the timeliness of the repair can be rejected if excessive considering how often the item is used. The protection can extend beyond the warranty period to what is the reasonable life of the item. The claim is against the retailer and their issues with the supplier are irrelevant.
After 13 days against an estimate of a max of 7 and with a Christmas shutdown imminent I contacted the regional manager. A few minutes later he called back with apologies, saying he would speak to the manager immediately and I could collect a replacement.
Similar laws apply elsewhere, and I found it useful to check it out and this may help others faced with ill-informed staff.