Daylight ******s

I transferred ownership of a number from a CC of which I am the sole member, to myself and at the time there was a substantial credit balance on the account. I have just received my latest statement which shows no record of this credit balance.. The slate has been wiped clean and I now owe an amount for the latest invoice. Where is my money. It is amazing how the account is still available on my profile on Vodacom login but the balance has suddenly changed with no history available on the account..