Telkom changing out of bundle settings resulting in a massive Bill

I am very disappointed in Telkom's fair use policy. I have recently done an upgrade with them. For some unknown reason the out of bundle options changed resulting in the line using airtime to purchase data. Telkom charged me R1381.35 for 7029 MB, more or less 7 Gb, that is almost R200 for 1 GB I can only state that this is very unreasonable and expensive..