Hello,
i'd like to offer you my prestashop skills. I can help you upgrade you prestashop.
I suggest to create temeporary subdomain where i will install latest 1.7 prestashop version, migrade all important data from 1.6 version and install theme.
After you approve everything i will have to migrate all data one more time to have new orders and customers and after that i can move this new shop from subdomain to live domain.
Do you also need to make changes in your new theme ?
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I work daily with prestashop over 6 years. I know prestashop from top to bottom. I am familiar with every aspect of this eshop system. From adding simple features, theme modifications, creating custom prestashop modules to overriding core files and connecting prestashop to various API's.
You can also check my other profile on freelancer.com where i have a lot more prestashop related reviews: https://www.freelancer.com/u/prestashop24.html
Thank you for your time.
Kind Regards,
Jarda Nalezny