Telkom causing us a major loss of income due to landline replacement

We have the new WiFi phones, the d-link phones. These phones have not been working at all, the signal jumps from no bars to 3 bars and all our clients have complained that they cannot get through to our business lines, we have been Telkom clients for years we had no choice in switching over to these phones from our landlines. I expect that you send a technician out because we are probably getting 20% of our normal phonecalls. Everytime I talk to someone in the technical department they tell me something different, none of them know how to fix this problem so you should make a plan as we are dependent on our landlines which we’ve had for 26 years we are losing 50% of our income. I have never experienced such horrific service.