When it comes to digital marketing and eCommerce stores, it's one thing to get the brand and strategy right and it's something else to make sure a site can take transaction after transaction so your customer gets paid.
We've dealt with many systems over the years from Magento to Shopify and when it comes to integration with in-house systems so that inventory and stock is maintained as a designer, copywriter or strategist your going to need members that know what they're doing with these systems.
The right solution first approach applies here while we'd love a local to help with this solution this may not be possible. If you know someone then we'll need to vet them to ensure their capabilities and have a proven history in this area.
We are more than happy to take feedback for these platforms and if you can offer something locally we'd be keen to have a chat.