Scam/ Forgry At NIPOST Office, Who Do I Report To?

Hello everyone, I need help on this issue. My fiancee sent her wedding gown from Germany( dutche post) to Nigeria(NIPOST). This morning I called the customer care and I was given a location to go pick it up. 1hour after that a woman called me to come pick it up but that I have a custom charge of about 29,000 naira to pay. I shouted and insulted her that even the amount they use to send it from abroad is not up to that. Immediately I went there and they insisted I most pay. I requested for a document to show the charges.

 She brought out a paper and what I observed, the paper was tampered with in their office. The good was sent as personal goods which doesn't attract custom charge so she was told in germany. The woman is feeling like God and I really want to show her, she can't do fraud and still wait for me to be begging her. Pls anybody with ideas on who to report the case to. Attach is the receipt she showed me and I took pictures of it. If you carefully look at it, the blue pen is what it came with originally and am to pay 2100 for delivery. The rest amount is different and was written with a red pen. Pls who can I report to, and am I suppose to pay custom duty for personal goods?