Product: Credit card or prepaid card

I made two purchases with a merchant with Synchrony Bank through PayPal Credit. One was for {$260.00} and the other was for {$480.00}. Each was done within a short time of each other and done by myself and the merchant in an identical way. Unbeknown to me the {$480.00} was put into the normal six month payment plan and due in XX/XX/2020 and the {$260.00} was put into some kind of cash program that I never heard of and was not asked if I wanted it to go there. I had plenty of credit available in what they call the Special Financing Program which gives six months interest free. I spent nine hours on the phone with Synchrony Bank last week and they could not figure out what went wrong. I figured out what went wrong and they clearly have an IT problem and mistakingly put the {$260.00} into the incorrect area, something they call a " cash payment '' which I have never heard of before. This is the first part of my complaint. 

The second part has to do with what they did next. On XX/XX/XXXX I paid {$300.00} to get rid of the {$260.00} and to pay the minimum amount due which was {$29.00}. so I do not get charged a hefty interest charge on XX/XX/XXXX. Instead of applying the {$300.00} to the soonest payment due they wrongly applied it to what is due next month on the 6 months with no interest plan. However, they had no trouble applying {$29.00} to the minimum amount due. I called them again and spoke with three people including a supervisor and I did not get any answer of consistency out of any of them which is why I am being forced to file this complaint. I am an XXXX  and I have an XXXX in XXXX  from the XXXX School thus I am not a slouch in understanding basic finance. Any payment should be applied to the soonest item due or someone would have to pay off their entire loan to get to the soonest amount due which would amount to an unbelievable amount of interest due. Synchrony Bank apparently does not understand or want to understand this though strangely they have it figured on in their Special Financing Program that they apply payment to the soonest amounts due. They have stated in an unapologetic way to me that a mistake was made in their software and yes my payment should have been applied to the soonest amount due which should not even be the case if their software worked in the first place with this amount being put on the intended six month plan. I have been not been verbally assured that any errors are going to be corrected before interest is charged on the {$260.00} on XX/XX/XXXX. I also have no faith in anything that this bank verbally says to me because they have said false things to me before that were simply not true, i.e. I can have until XXXX to pay off my amounts that are due on XX/XX/XXXX. Therefore the second complaint is that I want my payment of {$300.00} applied to the {$260.00} as it should have been so that no interest is due. I have attached screen shots of the {$260.00} still due, the {$300.00} that was paid on XX/XX/XXXX and the six month Special Financing Purchases and the XXXX that the {$300.00} was wrongly applied to and now wrongly paid off. 

This entire matter is a result of a bank that has a very XXXX up IT department or IT subcontractor that does not know what they are doing. I find Synchrony 's software and thus website to be very dysfunctional and then to add insult to injury the staff is very poorly trained and has no ability to understand the mistakes and has no desire to fix anything. The bank needs to hire some experienced bankers, especially at the supervisor level so that there is an ability to fix these problems when they arise. They all need training in how to handle customers, the customer service is about the poorest I have ever experienced. As. result I am going to minimize my future usage of this account because I can not continue to spend the hours on the phone that I have and accomplish nothing and be treated terrible in the process.