Withholding Funds that do not belong - Tarsus Distribution

I use Tarsus as one of my suppliers. I received a quote for an Acer X1127i projector from a different Supplier Rectron. I accidentally paid Tarsus and forwarded Proof of Payment. After realizing this I contacted the person who is in charge of my account and I was told I need to produce a bank statement so they can refund me. I did so and then got told that they need a bank stamped statement. I went to the bank and got it done, scanned, and emailed back. Then I gold told Tarsus needs a letter from the banking confirming my banking details and my company registration documents. Why because I paid with my personal account and I have given you the statement that you require and you can clearly see that I paid with my personal account which is not liked to my company, Why do you want my company documentation? But just because I'm not trying to be difficult I have attached both the stamped bank letter confirming my PERSONAL account and my company registration documents So I can get MY money back.