Allegiant review: I am supposed to have a credit on my account from a previous cancelled flight. I don't have that credit showing on my account.

I have made numerous attempts to contact Allegiant over the last few months. I have tried every form of communication suggested. I have not received a response in any form. Last year we had a member of our party that was unable to go on vacation with us and we had to cancel her flight ticket. I had the flex package so that allowed us to cancel without penalty and receive a voucher that was good for one year. We planned on using it this year to fly with them, but after trying to contact them in every way suggested I have yet to get a response in any form. No response email, no call back, nothing. I know I have attempted to contact them for at least the last 3 months. I was even willing to wait however many hours it was going to take on hold to be able to speak with someone, but now you get a recording that tells you that they are experiencing high call volume and to call back later. There is no option to stay on hold or even leave a message. They suggest to go online, which I have done more than once with no response. I also attempted to chat with an agent online and when you submit it says "Sorry, there are no agents available at this time". I have tried that numerous times and that is the message I get every single time. This is unacceptable. I realize everybody is short handed right now. But I work in healthcare as a nurse at a Pulmonology Clinic so I have little to no patience for excuses for being short handed and not giving proper care and customer service. Allegiant customer service is the worst I have experienced in a very long time. I am running out of time. I can imagine that IF I ever actually speak to someone they will easily say my voucher is now expired. However my first attempt months ago it would not have been. I need help with this ASAP.