Good morning,
Thanks for getting in touch, contacting your mobile network provider is definitely the best thing to do as they will be able to advise the options available to you. In terms of currency, yes, due to the restriction of only being able to take 5000r into the country, its best to withdraw from ATM's should you need anymore, there are plenty of ATM's available to use,
I hope this helps,
Kindest,
Ben