Invalid credit card on Paul Smith

I.goTo("https://www.paulsmith.com/uk")

I.click("Accept All")

I.click("Stripe")
I.click("Stripe")
I.see("Signature Stripe")
I.click("For Him")
I.see("Signature Stripe For Him")
I.click("Wool Sweater")
I.click("Add To Bag")
I.click("L")
I.click("Review bag & Checkout")
I.click("Checkout")
//Fill in needed details and choose desired options
I.fill("Email", "[email protected]")
I.click("Standard Delivery")
I.fill("First Name", "John")
I.fill("Last Name", "Kent")
I.fill("Address Line 1", "Sample Address")
I.fill("City", "Birmingham")
I.fill("Post Code", "A12 3BC")
I.fill("Phone Number", "123456789")
I.click("Go To Payment")

//Choose Payment and fill needed details
I.click("Debit/Credit Card")
UI.context("iframe[title='Iframe for secured card number']", ()=>{
	I.fill("Card number field", "4242 4242 4242 4242")
})
UI.context("iframe[title='Iframe for secured card expiry date']", ()=>{
	I.fill("Expiry date field", "12/29")
})
UI.context("iframe[title='Iframe for secured card security code']", ()=>{
	I.fill("Security code field", "123")
})
I.fill("Name on card", "John Kent")
I.click("Place Order & Pay")

//Check For Errors
I.wait(5)
I.see("Refused")