You could have found their address out by asking them in your many phone calls - it wont have changed!:
E2SAVE.COM LIMITED
3R House, Belton Road West Extension, Belton Road Industrial Estate, Loughborough, Leicestershire, LE11 5XH.
The Managing Director is/was Andrew Heddle but send it to him anyway. If the freephone numbers don't appear to be working, then use the landline options but there is no need to call them every day - you are wasting your own money.
The letter on the other link is for that person problem, you MUST change this to talk about your problem. Do you still want the contract and phone? If not, say you are "cancelling the contract because of the long delay in providing the service. You are "within your rights to cancel given you have paid for a service and not received it". If you do want to keep the contract going, state that "if you do not receive the phone within 10 days (of writing the letter), you expect all your money to be reimbursed". They want your custom, so they will get your phone to you asap.
Stop calling them and write the letter to them, send it to the address provided and wait until you get what you want or the deadline has passed for them sorting it out.