Product: Credit card or prepaid card

I've had my Discover business credit card under XXXX XXXX XXXX for about 15 years and never missed a payment or was late making a payment. It's my oldest credit card that reports on my consumer credit report!!! A few months ago I called Discover business credit card customer service and asked them if I started a new company can I change my business name on my credit card and I was told yes ... so I gave them the name of the new company I start in XX/XX/2023 which is called XXXX XXXX XXXX the address and tax ID number. XXXX new cards were sent out to me with the new business name and I had been using my card as usual then on XXXX, 2023 I went to use my card and it was declined. I immediately called in to Discover business credit card customer service and reach a rep by the name XXXX. XXXX told me my card had been mistakenly closed but it would be reopened on XX/XX/2023 and they had made mistake. I called Discover business customer service on XX/XX/2023 and spoke to a XXXX name XXXX and she told me it look like it was closed in error due to some type of verification and a supervisor would call me back never received a call back. I call on XX/XX/2023 and spoke to a supervisor by name of XXXX in Ohio and she tells me it looks like your card suppose to be re opened on the XX/XX/2023 according to the notes but it also states the card is permanently closed but she will speak with her manager and call me back. She never calls back!!! I call back get a supervisor in Delaware name XXXX and she states it's a lot of notes on my account that she needs to review and she will call me back but she never calls me back. Then on XX/XX/2023 my card is not reopen I call in and speak with a supervisor in Utah by the XXXX and she tells me my account is under review to be reopened and she will call me back by XX/XX/2023 with a answer. Never received a call back and my account is still closed. On XX/XX/2023 I call in because my account is still closed with no explanation and reach XXXX a supervisor in Ohio who states he's documenting my account to send to his manager that my account should be reopened because I changed the name on my card that I have had for 15 years because a customer service rep told me I could when I could of kept the name XXXX XXXX XXXX. He recommended that my account be reopened in XXXX XXXX XXXX since the name change seems like it caused the problem even though XXXX XXXX XXXX XXXX could be verified on Wyoming XXXX of XXXX website. He told me he would forward that information to his XXXX and call me back the next day with news about the account being reopened. Never received a call back so I call in XX/XX/2023 and speak with XXXX a supervisor in XXXX and he states my account cant be reopened and could not give me a reason why!!! Discover should not close my business credit card that I have had for 15 years and reports to my consumer credit report as my oldest credit account with no late or missed payments because the closing of this card will cause me financial hardship due to the age history of this account wont be reflected on my consumer credit report anymore. Discover should understand that a person never closes its oldest credit card because that will damage their credit!!! I'm stressed out and confused that a company that I've been with for over 15 years can close my credit card for no reason and choose not to explain the reason why.!!! I truly need this card to be reopened because the closure of my card is going to damage my credit!!! The last four digits of my account is XXXX. Attached is XXXX XXXX XXXX XXXX paper work proving its a legitimate company.