section[aria-label="Your order is confirmed"] > div > :is(h2, div) {
    display: none !important;
}

section[aria-label="Your order is confirmed"] > div::after {
    content: 'Thank you for your order, please call us with any questions or concerns' !important;
    font-weight: 700 !important;
    font-size: 18px !important;
}