want to create a page on my website from where i can send my customers a reminder

[Pagyal-Group]

want to create a page on my website from where i can send my customers a reminder

i have a service center business www.kentrouv.com and www.nearbyservicecenter.com i want to create something so that i can give my customers a reminder when there service is due,remind them by any means whatsapp,sms or email ,can someone suggest how can i do this,