Why is my UPI showing 5000₹ instead of the 20₹ Shopify plan in India?

[Zippbuy]

I signed up with this account on Shopify in India, and it gave me a free trial for 3 days. But in order to change some settings, I have to get the plan which is 20₹ for 3 each months. So I confirm the billing process that for 3 months I will be charged 20₹ and later the main plan. But when I go to the payment process of UPI, It shows 5000₹ to pay. What's the use of the 20₹ offer when I have to pay 5000₹ let alone 400₹ per month? Thanks for reading.