editing attributes link from cart

Hi, I had someone install a mod for me but it doesnt seem to be working properly.

Basically, I have some products with attributes but once added to the cart I wanted the option of the customer being able to edit their attributes choice, especially if its a product with engraving text, if they spot a typo they can correct without having to start over, or if they've chosen the wrong font from the font drop down, they can click the 'click to edit' link in the cart under the product and change the attribute options then add to cart and its updated.

But at the moment, the click to edit link is clicked and it takes them to the product page but once changes are made and its added to cart it just adds a whole new product to the cart, i suppose the answer could be for the customer to just delete the previous product the whole point is if they've spend a while typing an engraving message they would have to start again.

So how can I have the function to work properly? As it would be a very useful feature for customers when buying products with lots of different attributes, they can simply click and edit one element if thats all thats needed and then it updates the cart with that change.

My site is the great gift shop. co . uk

I had someone install a mod for me

So how can I have the function to work properly?
As this is not part of the distributed code, assistance here will be little to none....
If a contributed modele look for a support thread
Else, go back to who installed it