Why charge an Installation fee

I have app**** for a wifi phone. Its a lovely phone i must agree. Vox telecom wants to charge me R800 for installation but the phone is a plug and play. I said please install the phone then in my office at home and they said that is not how they install they only plug the phone in at the router and thats the installation.

so I have to pay R 800 for something that is only a plug an play and no installation to where I want the phone.

Is this how it works

when I try to call the managers the calls just keep on ringing