Product: Credit card or prepaid card

My name is XXXX XXXX and I am the XXXX  of XXXX XXXX, a wholesale distribution company in Illinois. I XXXX XXXX XXXX in XXXX and have been doing business with Costco since XXXX. I XXXX   XXXX from Costco then XXXX XXXX XXXX. Since XXXX I have been the number # 1 customer of their XXXX location store # XXXX in illinois if not the whole state, with purchases over {$20.00} XXXX a year from Costco. A couple of years they were even North of {$30.00} XXXX. 
Last month my Costco Citibank visa account was closed without any reason provided. i got the letter in the mail five days after the account was closed. I have made my payments regularly and never been late. When i called the Citibank customer service they did not know why it was closed and told me they were not required to give me a reason. 

My problem with them is if they wanted to close the account, they should have given me at least some transition time so i could arrange for an alternative for my customers till we figure this issue out. They also closed after 11 months of my rebate earned on my account, so that they don't have to pay {$270000.00} they owe me for the whole year. The manager of the location XXXX was very apologetic over it but said it is not in his hands. 
I have emailed the CEO of Costco and Citibank, all i got was a letter from the executive response unit stating i made too many payments on the account in excess of {$9.00} XXXX from XX/XX/XXXX till XX/XX/XXXX. I have to charge the account daily and make payments daily for me to continue to do business. But none of the payments have been late or have bounced. Since when did making payments on the account became an issue. The charges and payments are all electronic. 
I have been doing business the same way since XXXX and they never had an issue before. Even if they did had an issue all they had to do was tell me and i would have adjusted accordingly. They also stated that the rebate earned the whole year is held by them and if they close the account the rebate is forfeited. They don't want to pay my {$270000.00} they owe me in rebate rewards. They paid last year over {$300000.00} with me running the business the same way. 

Upon some research i found out that there are a couple of small companies that Citibank is doing the same thing to. They are listed as follows. 
XXXX XXXX XXXX amount owed {$37000.00} XXXX XXXX  XXXX XXXX amount owed {$29000.00} Ironically all the owners of the other two companies and me happen to be XXXX. 
There are other XXXX  XXXX with non XXXX owners still operating and using the card the same way we do. 
I want Costco and Citibank to come good on this and reinstate as i have been nothing but an ideal customer with them over past few years, and pay me and the other two people the rebate they owe. Citibank also has an Arbitration clause in their agreement so there is no class action law suit against them. 
I get no answers from Citi customer service. They did not even give me a copy of the signed agreement I signed during initial setup. I am getting no responses or answers from them. My account rep sent me an online link to the Credit card agreement which does not even mentions the forfeiture of the rebate. 
I feel this is happening to me because I am a XXXX and Citibank was recently sued by someone in New York for discrimination. 
The link they provided for the agreement is as follows. 

https : //www.citi.com/CRD/PDF/CMA/cardAgreement/Costco_Online_CMA_0118_vf2.pdf My company has almost shutdown because of this with very little business credit available on other cards. Same has happened to the other two companies one is out of business because of this and the other one is also almost done. They will be filing a separate complaint on this website separately as well. 
They also closed my personal XXXX XXXX mileage mastercard with XXXX points, that i had since XXXX. I only used that for personal stuff and did not carry a large balance on.