As an AI language model, I can provide you with some information about Shopify pricing. It's important to note that pricing may vary depending on the specific plan and any additional features you choose.

Shopify offers several pricing plans, including Basic Shopify, Shopify, and Advanced Shopify. The prices for these plans are as follows:

1. Basic Shopify: $29 per month
2. Shopify: $79 per month
3. Advanced Shopify: $299 per month

It seems like you are currently on the Basic Shopify plan, which is priced at $29 per month. However, you mentioned paying $39. There could be a few reasons for this discrepancy:

1. Additional Apps or Services: Shopify offers various apps and services that can be added to your store for an extra cost. These apps can enhance your store's functionality and may require an additional monthly fee. Make sure to review your billing statement to see if any additional apps or services are being charged.

2. Transaction Fees: Depending on your payment gateway, Shopify may charge transaction fees on each sale made through your store. These fees are separate from your monthly plan cost. For example, if you are using Shopify Payments as your payment gateway, you won't have any transaction fees. However, if you are using a third-party payment provider, such as PayPal, you may incur additional fees. Check your payment settings to see if any transaction fees are being applied.

3. Currency Conversion: If you are located outside of the United States, the pricing may be displayed in a different currency on the website. This could lead to a difference in the amount you pay due to currency conversion rates and any associated fees.

To get a clear understanding of your specific charges, it's recommended to review your Shopify billing statement or contact Shopify's customer support directly. They can provide you with detailed information about your plan, any additional charges, and help resolve any confusion regarding the pricing differences.

Remember, Shopify's pricing structure may change over time, so it's always a good idea to check their official website or contact their support for the most up-to-date information.