Product: Credit card or prepaid card

I have been citi 's customer for 3 years. My first citi credit card was approved in 2015, and I have been using that card since then. Citi sent me the advertising letter to ask me apply for a new premier card months ago, and said I could get XXXX thank you points if I spent {$4000.00} in the first months. That attracts me, and considering I will go travel and buy gifts for my girlfriend, I think I can finish that bonus task, so I applied that card and get approved this XXXX. Then I use the premier card normally, use the card for gasoline, restaurant, buying clothes and electrical devices online, pay all the balance before due, and never have late payments. I have been always kept a high credit score, around XXXX points for both XXXX  and XXXX. 

On XXXX XXXX when I try to use the card to load money to my transportation card, it said the transaction failed. I then login to my citi account and finds all my credit cards are closed by citi. I then call the citi customer service, and they give me no explanations. Just said I will receive a letter and ask me to wait for the letter. Several days letter, I received the letter, and again no explanations, and it asks me to sent letters to citi to ask for explanations. Ok, I sent the email to citi and hope they can give me reasonable explanations. 

I really have no idea why citi close all my cards. I have never use the credit cards inappropriately. I never have late payments. I always keep my credit use under 15 %. Citi got every right to close my account as long as they want. But when they arbitrarily close my account without any warning or explanations, they also take back all my thank you points. Those points are earned by myself. I spent every dollars to earn those points and they just take all those points away as they want. 

I then chat with the online customer service to ask issues regarding my thank you points. The customer service told me " you will get the access of the thank you points, you just need to call our thank you team once. I will share their number. you are not able to see the points because of the status of the account. rest assured that you have it in your account. ". I then get the thank you team 's number and called that number and a lady answered. I explain what happened, just exactly the same I told the customer service through online chat. But the lady said I can not get those points. I questioned that citi got every right to close my account, but why they can take back my points. I earned those points by spending every dollars. And they never show me any policies that citi got rights to take back all thank you points after they close my accounts. The lady answered me very rudely, she said " Yes, we can do this. We can do whatever we want. You will not get those points ''. That really XXXX me off! I then hang up the phone. 

How can citi, a large credit card company, do such thingsThat 's exactly robbery and deception for me : 1. First of all, if citi didn't send me the advertising letter, I will not even consider to apply for my second citi credit card. 
2. Second, citi got all rights to close my account, but at least should give me some explanations. My first credit card have not been used for like 5 months, and they suddenly close all my credit cards. I NEVER use the card abnormally and NEVER have late payments. 
3. Third, yes, citi have all rights to close my account, but how can they take back all my thank you points?? I never find any terms or policies says they can arbitrarily close any customers ' credit cards and then take those points back. Those points are earned by myself by spending every dollars. I can use my other credit cards, like XXXX or XXXX, I will still get points. But since citi sent me the advertising letter and let me to apply for Premier card, and told me I will get 60K thank you points bonus after I spent {$4000.00} in the first three months, I then only use the citi premier card in my daily life. That's a huge loss for me. Citi 's behavior is really like a robbery in my eyes. 
4. Fourth, the third customer service 's attitudes were very poor and rude. She never tried to solve the issue for me, or gave me any specific policies or terms showing they have rights to take back my points when they close my account. Also her response to me is very RUDE! I even doubt whether because my accents sound like a foreigner so that she said those rude words to me. If so, that's RACISM! 
5. Fifth, I maintain a very good habit in using all my credit cards, and have been always maintain a very high credit score. Citi arbitrarily close my accounts will hugely affect my credit score, and will further affect my loan interest if I will lease a car or buy a house in the future.