Since you're getting a signal through everything else when the Tremulator is bypassed, the problem has got to be in the pedal. First thought would be to check your power supply, or battery, as the case may be. If swapping those doesn't help, you may have a bad pedal.
If you have a good relationship with a local music store, you might take it around to them, and see if a different power supply makes any difference, or if they're aware of any issues with that pedal. Otherwise, your next move would be to return the thing, and get your money back.
I see that you're in England, so I can't be sure what's the best avenue for you to pursue. Certainly, contact the seller, and see what kind of response you get. If that's no help, you can try to work through ebay, or through your credit card company. Over here, after a rash of consumer complaints, it's somewhat easier for ebay buyers to get refunds for their purchases, especially if you've paid through their paypal service. A number of credit card companies also offer buyer protection, so contact your credit card company, and see what they offer.
Best of luck with this.