Product promotion countdown

I'm new to OpenCart and I'm trying to bu开发者_Python百科ild an ecommerce website. I want to show the time left for my promotions and I don't know how. When I have a product with a promotion I want to show the time left to the ending of it ("countdown: 3 hours and 23 minutes").

I've seen some examples (http://www.opencartaustralia.com/recycle/) but the problem is that when the time is over the product becomes unavailable. I just want the product to revert to the old price.

I don't know if it's any good, but here's somebody selling a countdown bundle for opencart for 38 USD: OpenCart Countdown Timer Bundle.