Unreleased funds

I previously received funds from Old Mutual 2 -pot system into my FNB account, since i have been retrenched my pension fund from the pension administrator send my pension money into FNB using the same reference they used for 2pot pay-out. They are refusing to release my money saying the want proof of payment and source of this income. I have been sitting for 2 weeks waiting for them to release those funds which has same reference as the 2 poet system which is showing funds coming from same place. I need my funds released i saved that money over the years and now FNB refuses to release the fund.