Hi,
My Name is Shail and I am having 10 years of experience in PHP and LInux. Please Hire me, I will upgrade your both shopping cart.
Procedure for Up-gradation :- I will make the test server of both your cart and then Update all files one by one, each file will be compare line by line and replaced with the new zen cart functions.
After that, I will upgrade the database, if there is any upgrade for table changes
In this way, we will ensure that there will be no error and we will test it thoroughly on test servers
Let me know when i can start
Thanks