Greyhound Refusal of refund, supposedly never received my request, Internet

I had purchased a round-trip ticket to Florida in order to visit a friend. The trip was cancelled and I sent in my tickets, along with a letter requesting a refund, to their post office box as the website instructed. This was at the beginning of April, on the 2nd. I hadn't heard anything from them during the whole month of April, so I chose to contact them via email on April 27th to query as to whether they'd gotten my request or not. They claimed they had not.

So, I asked if I should contact the post office to see that my letter got through to Dallas, to their company. The post office said yes. I sent off this information, along with the ticket information that was emailed to me, asking for the company to find my letter. I have the strong belief that Greyhound is lying about receiving my letter and are using any excuse not to refund my ticket of $192.00. After reading many of the other letters from individuals who have experienced similar situations, I'm 100% certain that my request was secretly denied.