overchargd twice!!!!

I reported on 2 feb about being overchargrd by cell c. Maropeng rep**** and called me saying that i will be credited the amount i ws overcharged. Up till now i have still not receivd the credit in my account bt hav jus receivd a new statemnt informing me of a cancellation fee. This is the worst service ever especially since i did not request the cancellation. ive tried callin to enquire abt my credit, hav receivd no response. I demand to spk to manager!!!