Builders Warehouse

I made an online purchase of a gas panel heater from Builders Warehouse. After the due date for delivery, I was informed that there was no stock available, despite there being stock at the time of purchase and payment. The gas panel heater was eventually delivered albeit late. It is defective. I have written 2 emails to Builders Warehouse. Although they have a standard automated response that reads: "We are working on your request and will get back to you as soon as possible, normally within 48 hours", that response is false. It has been 10 days since I wrote to them. So much for 48 hours. Such standard response is really no response at all. They do not explain their delay. They do not deal with the complaint. They have had the benefit of payment (which includes the delivery charge), yet I have a gas panel heater that does not work. They are in breach of the Consumer Protection Act and our contract. They have done nothing to replace it. Their conduct is shameful. It is apparent that they do not respect consumers' rights.