Billing on my account

Although I have call limit on my account and receive sms's from Vodacom that my phone will be soft locked on the 23/5/2015 because I have exceeded my voluntary call limit., they still charge me R355.91 xtra for additional data used!!!! AND they locked my phone until the end of the month???<br> now, when I phone to querry my bill, they say there is no record of a call limit??? This is the 2nd time this happened to me. <br> I want Vodacom to pay back the R355.91 and make sure their system is up to date.,