Unable to provide ********* details

I am in the process of taking on a ********* who de*****ed me on Gumtree, the phone number used by the ********* was ***. I have an official statement from the police. The ********* gave me a standard bank account number ***. Standard bank refused to provide and information on the ********* and told me that I am not allowed to conduct an investigation myself. I spoke to the lady at the hello desk. I am not impressed that they are not willing to help me and even worse, they are not willing to take on ********** who use their services to commit *****.