just to activate my number

Iv been struggling to get my number back everytime i call the call center they give me a security question but i cant remember when last i recharged or the last 3 calls iv dialed i keep failing this test and i really need my number due to clients calling me. but cellc keeps telling me to try remember the last time i recharged and etc im just not winning for my number. its weeks now and still i dont have my number