Why give my prepaid number to someone else?

I had my prepaid number for the last 15 years and got sms's today that my number has been converted to contract. When I phoned I was told this number belongs to someone else and my details were deleted. Also that it is a contract number now. I spoke to Nomceto and explained the situation since it is month end I will be in a predicament with all my debit orders and other stuff. She advised me that it will take 24 - 48 hours to have it fixed and I must ph back to find out when it is done. No 1: I did not make the mistake why must I follow up? Please sort out this mess as I need my number back urgently.