Product: Credit card or prepaid card

I have a credit card store account with XXXX XXXX that is with Synchrony Bank. I've had this store card for about 4-5 years and have had this on reoccurring debit for the payment since a month or two of originally obtaining the card. I've never been late. However, on XX/XX/XXXX, I changed my reoccurring payment amount from the minimum payment to a payment of {$100.00}, which is more than my minimum payment to help reduce the principal balance faster. This is in addition to reducing it by {$1000.00} with a balance transfer from another credit card that has a lower interest rate in XX/XX/XXXX. My credit line availability was {$3000.00}. When I changed my monthly payment amount, I wasn't notified that the change could take 30 days. I didn't think of that at all because it didn't take that long to change my banking information for the payment in XXXX/XXXX of this year. It took that information change immediately. Since the system didn't process my payment, I was charged a late charge of {$25.00} and my credit line was immediately reduced to {$100.00} above the credit card balance. I called Synchrony and they said that it was because of my outstanding credit card balances. However if that was the case, they would have lowered my credit line sometime in the last 2 years because my balances did become high. I'm in the process of payment my debt down. I paid off my car and have been making extra payments on my unsecured debt, thus the higher payment on this card. They just informed me that they pulled my credit on XX/XX/XXXX, but didn't make a decision until XX/XX/XXXX to decrease my credit line, but then again didn't mail a letter regarding that until XX/XX/XXXX. Since their system didn't auto debit correctly when I increased my monthly payment, I was charged a late fee, which they have refunded. However, I'm more concerned with the fact that they lowered my credit line and therefore dropped by credit score even further ( after I've paid them down 33 % in XXXX and making more of a monthly payment which I did prior to what I was told the date of decision was on XX/XX/XXXX ). If the law regarding reduction of credit isn't helpful it should be changed. I would have understood if the decreased my limit at some point in the last 2 years, but they didn't. They decreased it after the 1st late payment, which was their error and they refunded the late fee. I'm trying to reduce this debt and others to improve my credit and I've NEVER been late on this account since it was established. I would think that there should be a time period between them actually pulling an updated credit report ( whether it's a soft or hard hit to the credit ) and making the decision. I know this an automated process so why did it take in excess of 45 days for them to mail a letter form the date of them pulling my credit. And it just happened to be after a late payment, which was their error. I can provide a history of reoccurring payment on this account and where I immediately made a payment when I realized the reoccurring didn't process correctly. I realize this is a big company/bank and they are connected to XXXX, but that shouldn't matter when consumers are actually trying to reduce debt and improve their score. Again, it would be different if they'd have done this in the last 2 years because my credit card debt has been high throughout that time period as well.