New Wi-fi landline is frustrating

We were issued with a new wi-fi telephone to replace the existing phone that we used for our landline. This is really frustrating. My other portable phone is not working anymore. The new phone is portable, but very big and not user friendly at all. We received minimum information from Telkom regarding the new service, no manual that comes with the phone and how can we add more phones. This is really an unsatisfactory situation, and I am considering to cancel my service with the company.