Data Roaming charge

I was charged about R18,000 worth of data usage on 15 August 2017. Vodacom so far could not explain or attend to my enquiries saying I must wait for the billing period to close by 4 September. All enquiries had to be directed to their 082111 helpline. Background: I am a contract user on 'Red Advantage' package. I travel overseas regularly for work, about 6-8 weeks per year for the last 15 years. The one thing I have always managed and be aware off is my overseas data usage because of cost associated. My phone & data roaming is switched on but I limit the apps to the ones I can 'control' and open - being whatsupp and messages mainly. Actively in hotels / offices switch to wifi and do emails that way. That has always kept cost under control. On 15/08 we were in Toronto, Canada. I received an sms from Vodacom indicating that data usage amount to R18,000. I followed the same procedure as before, checked all apps etc. For rest of week in Canada this did not happen again. My enquiry at vodacom has been met with the same response 'a credit is due but we cannot tell you how much till please wait to 4 Sept for billing period to close'. My question to vodacom is simple, I want to understand time and preferably which app/product caused this data surge and don't want to wait until I get billed to recover the amount again. I don't accept the current charge and lack of assistance and details they provide. After being a client for almost 20 years that is nonsense. Normally my overseas roaming bills vary between R2000-R4000 for a trip of 1-2 weeks. thank you