It's quite possible that the folks at zencartbuilder may not be engaged in providing those services anymore.
If your purchase was "recent" and you're unhappy with what you bought, you may be able to request a refund via your credit card company.
That said, zencartbuilder is not affiliated with zen-cart.com in any way, and you will need to address your concerns with zencartbuilder directly.
While you may be able to custom-code the required changes to make that very old version of EP work with Zen Cart v1.5, you would be better off using a currently-supported version such as discussed earlier in this discussion thread.
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