Readymade WhatsApp Clone or Custom Build — Messaging App (Mobile + Desktop + Browser)

We're looking for a developer or team to help us acquire and customise an existing WhatsApp-style chat application to match our specific requirements — rather than building entirely from scratch. Preferred... (Budget: £250 - £750 GBP, Jobs: Android, API Development, Cloud Computing, Database Management, Desktop App, Desktop Application, iPhone, Mobile App Development, PHP, Web Development)