TLS sends me from pillar to post. I am furious!!!

The TLS call centre sucks! I missed my appointment in Cape Town on 25.6 and am trying to rebook an appointment. I phone them four times so far and these are the instructions I received: 1. Change your email address and reregister 2. The next day - don't change your email address the appointment will be automatically cancelled after 48 hours 3. The next day - I will send an instruction to cancel your application - wait 48 hours and then rebook. 4. Today - You have to use a Microsoft Edge browser, then log in and delete your application.