Refund Issues

For the past two years I have been trying to get my refund from the institution but with no success. I have on multiple occasions furnished the institution with documents they require however they always want some or other document that was not mentioned previously. I have since lost access to the institutions email account along with all the emails. Currently they are requesting a bank statement from two years ago which i cannot get even when calling the bank. I don't understand what is so difficult, I was the student, I made the payment and the Institution has all m information, why is it when they have to refund me then all of a sudden there 5 documents I must send to prove the account was paid? It is draining and I have had it. These documents must be requested when I have to pay the institution as well so that everything is in order should there be a need for refund. The amount might be miniscule but it is mine! I am very disappointed in the institution's financial department, they have displayed a great deal of lack of willingness to have this resolved. Two years is a long time to be struggling with this matter.