ABSA Insurance/wills wasted R70 of my prepaid airtime and forced me to abort the call.

I phoned the wills dept of ABSA insurance to correct that was made in my will. I hung on for 18 minutes listening to music. This cost me R70 air time. I'm on pay as you go. I question whether the excuse that I kept getting of 'experiencing' high volume. Surely this is unacceptable. I need to fix a mistake that they made. The ID number of my sole heir was entered incorrectly. There can't be any acceptable excuse for making a client and running down their airtime. It makes it very difficult to communicate with them.