Airtime disappearing!

Was contacted by a Luyanda Mahali,from vodacom. He said n phishing group called gamelords,stole my airtime.I paid R110 of airtime, it went down to R39.The difference: R72.He said,he will block these gamelords so that they will not take my airtime anymore.He said he will pay the difference in my vodacom account. He paid in R50, not R72.How many times did this gamelords take my money before!! Why,did I have to pick this up before they did something about it??Why did vodacom not identify this,corrected it promptly and inform me about it??Is this vodacom account not secure? I received an sms from vodacom,saying: "Dear Vodacom Customer. Your service ticket with reference number EC-1LYH-1NMDNG has been closed. Thank you Vodacom." I was not asked if their services was satisfactory!!