How do I upgrade shipping files only from 1.5.3 to 1.5.4 ?

[Andrew H]

Nobody has answered my other post so thought I'd try again. I really would appreciate a little guidance here...

 

To cut a long story short, I have a LOT of problems with my shipping features, many bugs. The biggest one, often when I make an edit to the shipping carriers in the back end, the front end randomly disables ALL carriers so "there are no carriers" message appears (very frustrating).

 

I'm using 1.5.3. I'm thinking a lot of the problems I get might be ironed out by upgrading just the shipping-specific files, but I don't know which files I should upgrade? (I don't want to do a full upgrade since I've spent the last few months sorting out all the other problems from my previous upgrade)

 

 

I imagine this isn't a difficult question for someone who knows what files I need to replace....?

 

Thanks!