Brand new firearm sold twice

I am writing to Dave Sheer Bremaly, to explain about a bad experience I was subjected to. It is appalling to witness an employee ( Kenny) of such a respected renowned company to behave in such a manner. At first he sold me a firearm that belonged to someone else, then later on during the process picked up that it was sold in another branch. I insisted that he order Glock 19 Gen 5, I told him I wouldn't mind the waiting. Within a few minutes there was a gun available of which I was also pleased. Then he sorted out the paperwork for me. A month and a couple of weeks late (26/04/2021) I get a phone call from my local police station notifying me that my application cannot be processed because the firearm with serial number belongs to someone, so basically Dave Sheer sold the same gun twice which is fraud according to my understanding. I then contact the store immediately from 09:00am, I called approximately six times and was told he was at the rest room. I left a message for him only then around 10:30am he called me back. I expressed my grievance and demanded answers but he was not moved and told me he would get back to me. When he called me back I was hoping to get proper feedback with a solution, However, he just gave the one option I needed to take of a different pistol (Glock 17 Gen 4) of which I have no interest because I wanted to know what happen to the one I paid for on the 13/02/2021.Which is exactly what I want. I don’t know which system does this store use but such mistakes are unacceptable given the fact that you are dealing with delicate things such as firearms. I find this unacceptable because he never called me back to resolve the issue, nor have the audacity to acknowledge the fault and me running around trying to get hold of him of which I gave him ample time. I feel disrespect, unheard and unprioritized as a customer that has already paid especially. This is a huge inconvenience for me, as I will have to restart the licence application.