Poor service delivery. Poor customer service.

I purchased two windows in December 2021. Paid. Two weeks later one window was delivered. After I had to follow up, I was informed that the other window was not currently in stock and that they would receive stock in January 2022 upon opening after the holidays. I waited. No feedback, No calls, No updates. By February 2022 I called again to follow up on my missing window, had still not been delivered (For which they had already received payment). In March 2022 still no second window received. I then requested a full refund and for them to collect the previously delivered window They have since collected their window, but I have received no refund. How can such a big business operate with such poor service. How long do I still have to wait for my refund? How many of your platforms do I need to contact before any action comes of it? The staff to which I have spoken do not seem concerned with my refund at all.