Product: Payday loan, title loan, personal loan, or advance loan

In XX/XX/XXXX, I called to answer a letter that said I would get a free {$25.00} XXXX gift card for calling them about their water service. They immediately set up an appointment and said they would have to come in person to give me the gift card. So the guy came in, gave a hard sales pitch, promised all these free things like soaps for XXXX years, additional {$200.00} gift card, a shed, etc. He said he would give us the best price, about {$7500.00}. Well in the end it comes to over {$12000.00} because of finance charges, which were not adequately explained to me. It wasn't until I called in XXXX to ask if I made payments more than the minimum amount would it go toward principle. He told me that I can but it won't matter because I am being charged interest every day, and it will not make a difference. I told him I was not aware of how this works, I was told by the sales guy that I can always pay more and it would bring the balance down. Also, I was told in XXXX by the sales guy that another perk would be that I would have XXXX  months free where I didn't have a payment due until my first payment in XXXX. He didn't mention that at least {$2.00} a day interest would be charged from that day on. So here I was not making a payment until XXXX thinking I would be fine. And all along they were just adding up all the interest charges, gouging me to the core. 
Then today, I find out that XXXX XXXX has been calling me left and right saying that I am XXXX  days over due on my payment. This is a bald face lie! I made an effort to make my payment early on XX/XX/XXXX ( it is due on the XXXX ). I even have a screenshot to prove it. I tried paying by phone, but it would not let me make a payment saying they were closed ( it was a Sunday ) so I tried to do it online. I tried several times to log in and it kept saying it did not have an account with the account number and my phone number that I entered XXXX separate times, so I finally had to enter all the info as guest. So I am thinking all is well. Then XXXX XXXX starts calling me on XX/XX/XXXX saying I am late. I immediately called them but I was on hold for XXXX minutes then someone picked up then hung up. I tried again on XX/XX/XXXX and I explained to the guy that I tried paying on time, XX/XX/XXXX and I had the screenshot proof and I don't want to be penalized. He kept being rude ( his name was XXXX, the same guy that told me back in XXXX that it didn't matter if I paid more than the monthly amount, it wouldn't make a dent ). He said I needed to show my bank statement or they could not help me. I told him that their system is faulty and there is something fishy going on and I have the proof that I tried to pay and I shouldn't be penalized or charged fees or interest on the amount, and he would not listen he kept being rude and condescending so I asked for a supervisor and he put me on hold for XXXX minutes and came back and said one wasn't available supposedly. They just didn't want to help me. Because he was so rude and disrespectful, I asked for a women representative. I tried explaining that I tried making the payment, something is wrong with their computer system if it didn't take my payment but pretended it did, and again, she told me that I would have to provide my bank statement as proof, they wouldn't take the screenshot proof from their website. This is all very scandalous and unethical. They won't even look into why their computer didn't take my payment or if it did, where was it applied to. They use dishonest and deceptive practices to lure people to buying their water softener system. They price gouge and rip off people XXXX. This is a disgusting way to run a business and if I had to do it over again, I would never have purchased from this vender or used this finance company and I want to warn everyone to steer clear of XXXX XXXX XXXX. They keep getting shadier and shadier by the minute and I am so disgusted by these people I am sick to my stomach. It was bad enough how they bamboozled me to by their product, now they want to extort more money from my by having a glitchy computer system that doesn't take or apply payments so the customer ends up paying even more fees. Shameful and pathetic!