being billed incorrectly

I moved from South Africa to new Zealand on the 23rd December....I'm being billed for my handset (which I don't mind it's on contract) but also being billed for calls.....I NEVER MADE.....I send a mail to Marion and she's telling me the calls I'm being billed for is for 01.02.2014. OMW.....how can that be,,,a year later!!!! I'm in nz and never used my sim card here!! been using a nz sim card..so no calls can be billed to me from the 23rd dec 2014. and I expect them to pay me back. I don't have income in sa anymore, only a trust paying me but that can't all go for Vodacom!. please help me sort this out. please mail me with feedback. [Email Removed]