Call limit not activated

I upgraded my 3G contract to a 10gig + 10gig contract with a wi-fi LTE router. The upgraded package started on 1 August 2015. On 1 August 2015 I phoned vodacom customer service to activate the call limit on this line, not to exceed the 10gig limit. I was emailed the terms and conditions and accepted it. On the 28th of August 2015 I saw on my cellphone app that there is still 1 gig data left. On 31 August 2015 I saw on my app that my bill for my 10gig contract is R3400. I phoned the customer service and logged a complaint. On 1 September 2015 a customer service agent phoned me back to inform me that almost 4Gig of data was used on 29 and 30 August 2015. I do not know who used this data, and the agent told me it must be a device known to the wi fi router. I was informed that the data has been used and that Vodacom will rewrite the account to a 3gig data bundle. I was also informed that the call limit was never activated. The agent also told me that the call limit application is not a very reliable application from Vodacom and that I am respnsible to keep in the limits of my data. If the call limit was activated, my data would not run over the 10gig supp****. very upset!