Complaint sub-issue: Can't use card to make purchases

I attempted to use my Citi double cash back CC to pay the final invoice for a new roof for my house which totalled over {$6000.00} but was still well beneath the available balance on our card. Last month I paid the same exact company a deposit for the work which has already posted to my CC statement. The transaction this time for the remaining balance would not go through. I immediately logged online to see what the problem was and received a vague message saying that they suspected fraudulent charges and to call the phone number provided. I am an authorized user on the account but the representative said they could only speak with the primary account holder, my husband who is currently in XXXX. I explained that he was XXXX but had authorized me to use the account and that I can confirm the charge, which was on my card. The representative literally just repeated over and over that she could only talk to the primary. I tried relentlessly to explain that he can not just pick up a phone because he is in XXXX. I was given no other option, no email or online verification process or anything. She transfered me to her supervisor who was beyond reprehensible. I have never experienced such poor customer service. I was extremely distressed and in an incredibly vulnerable situation with my husband XXXX and they offered me no options, sympathy, or advice. I asked repeatedly for an explanation of Citi CC policy for authorized users, what rights do authorized users have in general and she would not tell me anything she just kept saying she couldn't talk to me at all because I was not a primary account holder and she refused to transfer me to anyone else. She finally said I could send in my power of attorney to be able to access the account but the only option is mailing it to a PO Box address and then waiting 5-7 days after they receive it for processing before they will even tell me what is going on with the account in the first place, let alone unlock it. After several distressing messages to my husband he tracked down a phone to call the number Citi CC gave us for him to be able to unlock the account, keep in mind he is calling long distance from XXXX. When he called they STILL refused to unlock the account and verify his identity because they couldn't call his cell phone number that is listed on the account!!!!!! He gave his SSN and answered every other question and because he can't answer his cell phone they wont confirm it's him and refuse to unlock our account or even say what the XXXX is going on in the first place. How is this fraud protection benefiting us??????? They said they would have to mail a letter to our house with a verification code that my husband will then have to call back from XXXX to Citi and tell them the code to unlock the account. So again our only option is to wait 5-7 days for something to travel in the mail. The entire reason we got this CC was to pay for our roof with 0 % interest while we wait for reimbursement from our home insurance company. Now I face having a late payment and screwing over my roofing company because my credit is tied up on a card I can't use. We had several different options for 0 % interest but now we suffer the consequences of a hit to our credit if we walk away from Citi to open a different account or the potential of paying interest on the balance using one of our other cards while we wait for reimbursement. I simply can not believe that this company has no other way to resolve an issue like this. We weren't even the ones who reported potential fraud. I simply tried to use my authorized card to pay a vendor that we paid before with no dispute. My husband called from XXXX gave all his identifying information. I stated the exact charge that I tried to make that they froze the account over. How can they justifiably keep us locked out of the account under the guise of fraud protection when the only thing we couldn't do was answer my husband 's cell phone number or read a text message because the service is disconnected because he is in XXXX!! What on Earth do we do?