Telkom mobile gave my number to someone.

I bought 100 airtime. When I check the balance on the phone it shows that I have recharged.bt when I use it on the laptop it says there is no data. When I called their call centre they told me that my Id no and names don't match with the sim number and she can't help me with anything.she promised to call me back but she did't. I have been using the simcard from last year.I only started seeing messages that are not mine early this month.my 250mb will not even last for a day. I am sharing a number with someone.