Installation date rescheduling nightmare

I ordered a Telkom landline on 23 Jan. I received an sms with an initial installation date, which I rescheduled to a LATER date which suited me. On 29 Jan I received an sms confirming my appointment for 1 Feb, as I had requested. A short while later I received another sms saying that a technician will install the line TODAY!!! I then try to reschedule back to 1 Feb and am unable to, and when I eventually get through to the call centre I am told the next available date is 8 Feb. I have taken leave and made arrangements, but now Telkom cannot help me and I need to make new plans for the date that is convenient for Telkom. Seriously??? How can you reschedule an appointment and only inform me on the day and expect me to be available??