Walmart Family Mobile Charging me for two lines. I have one line. Las Vegas, Nevada

Icalled Family Mobile to cancel one of two lines then activate a new device with a new number. This was on 12/2/12. The representative told me my billing cycle was on the 26th and other phone would automatically deactivate. On 12/12 I received a text from Family Mobile stating my new phone number was 702-234-4132. I was given the number 702-234-3439 on 12/2 and that's my only phone. I'm not paying for two numbers since I only subscribed for one.

The original cell numbers I had were 678 area codes and one was cancelled completely. The other had a number change.