Charges

I don't know what or who you are. But after buying sim card I was repeatedly told I was running out of money and to recharge my account which I could not understand why. I have pay as you go.
I checked my call details and discovered continues lists of airtelw ap.es who I never asked for or ever heard of.
After contacting vodafone they repaid these charges to 36 Euro's thankfully before throwing my phone away because of the expence.
How did you enter my phone and charge me when I never used it
I used my phone to ring people 20 times in one month which cost very little all the other charges were yours
Please explain