How do i contact seamless customer service? Although Seamless is owned by Grubhub, it still operates as a separate platform, which means Grubhub customer service won’t be able to help with Seamless orders. You can contact Seamless by calling (800) 256-1020 or by emailing [email protected]. 2. How can I call Grubhub if I run into an emergency?How can i contact seamless invoice support? Our invoice team can help existing corporate clients with any invoice or billing related questions. 020 3318 1875 (or free on 0808 189 6559), option 5 or [email protected] How do i get started with seamless? Fill out our Get Started form, email us at [email protected] or live chat with us now! Please submit a Forgot Username or Forgot Password form if your company has a Seamless Corporate Account and:How do i contact grubhub customer service for seamless? Although Seamless is owned by Grubhub, it still operates as a separate platform, which means Grubhub customer service won’t be able to help with Seamless orders. You can contact Seamless by calling (800) 256-1020 or by emailing [email protected].