Zen Cart Shipping and Payment Need FIX

We have a Zen Cart store and have some issues and fixes needing done. The fixes are for the Google Express checkout to work properly, must know how to configure Google Express fully. Paypal Express is experiencing errors before purchase action. Shipping methods we have in place are two sets of flat shipping rates one set for UPS and one set for Fed Ex. Three options only each All shipping quotes/or defaults costs should carry over and add to totals before checkout in all forms of payments, register enter CC, Google Express, and PayPal Express. These are quick and easy fixes for the person who knows it well. ONLY the lowest bid will be considered. Must use skype and have the ability to perform full test purchases to be sure everything is correct. We already had paid another developer to do this and we got burned and it was not done right. Is there anyone out there that knows what they are doing that is affordable???