I have heard of many stores turning over $2 million in sales via Shopify!
But I understand you're having a difficult time with SEO and agencies in the UK. I am the founder and CEO of Pynely. Which is a social media agency focused primarily on small-mid size eCommerce businesses.
We offer a highly focused and creative approach to social media management aimed at small businesses. We help manage social channels such as Facebook, Twitter, Instagram, Pinterest and LinkedIn and keep creative and engaging content flowing at peak times for your industry and audience. We also offer management of ads for Facebook, Twitter, LinkedIn and Instagram, social media profile audits and creation, monthly or weekly blog content services, and influencer marketing.
We offer fixed pricing that starts at $995 but if you're a Shopify store owner we are offering a $200 discount on all our social media packages.
You can find out more about our social media services at https://goo.gl/jeMZLb
But we also offer SEO services as well. If you're interested I would love to talk to you about how we can help you and give you a custom quote!
Yes, I am sure Shopify can as an e-commerce platform. However, with that being said you need to be able to drive traffic to your site that actually converts. It sounds like you need to ditch your digital marketing agency and look elsewhere.
Let me ask you this on average how many visitors does your site get per month?
Sounds like you might need some conversion optimization help. Do you have a proper Google Analytics set up with micro and macro conversion points properly tagged as events and goals set up? Do you have heatmapping, click tracking etc software set up as well?
I would start there and look at how I could improve based on those data points. Then I would consider implementing a survey based on issues or questions I would want to answer.