Voluntary call limit set incorrectly

I had a call limit set on my Data contract which has always worked without issue until Feb 2016 when my contract was allowed to go way into OOB... <br> <br> When I queried this I got some BS excuse about the service not being guaranteed, yet it worked every time before. I never received any usage sms until after I had already gone into OOB. I was on & off the web multiple times so how did the system not update? & even when the system did update, the lock was not activated & so I ended up with an insane bill...<br> <br> I think it is a pathetic attempt to offer a service to clients & when the system fails, the client has to pay! If the service is not guaranteed, then why offer it? Vodacom always out to ***** the clients using BS excuses when THEIR systems fail! This is just completely unacceptable!!