Debt collectors are being hired by a UK auto firm while I'm in the US

About 3-4 months ago, I traveled to the UK for over a month and decided to rent a car since I have a valid license, and the rental company accepted it. The initial representative I spoke with provided us with an automatic car because I don’t know how to drive a manual. She had me sign the paperwork and took a copy of my ID. She mentioned the car used regular “gas,” which confused me because I know many cars abroad use both diesel and gas. When we got to the gas station, we opted for diesel since it’s commonly used. However, the car didn’t actually run on diesel and broke down after about half an hour. They had to come collect it from the road. According to the contract I signed, I was liable for £1,400 if anything happened to the car, which I couldn’t afford to pay all at once, so they offered a payment plan.
After the incident, the same representative told me that the payment would only be around £200-£300, and she repeated this over the next two weeks. Suddenly, her male coworker started calling me, saying the amount was now £800-£900. Then, during the last two weeks of my stay, they raised it to the full £1,400. When I returned the car, the employee claimed I might have to pay more and whatever else was “owed,” which didn’t make sense because the contract clearly stated it was just £1,400.
I left the UK and returned to the US about two weeks later. The employee began emailing me, recommending that I pay £25 a week to settle the amount. He then requested my credit card and bank information through email to charge me weekly, which I find unusual since I’ve never heard of a company doing that. Now, he’s mentioned that the owners (if he’s not the owner, why am I not in contact with him?) will be contacting debt collectors, and I’m wondering what will happen if they do. From what I understand, many debt collectors only pursue debts if they believe they will recover their money, especially since this is an international situation. I’m considering just letting them handle it, as I could choose my weekly payment amount and deal with a legitimate company instead of this questionable car rental agency.
Edit: I’m not looking for anyone to reprimand me for putting diesel in the wrong car; I acknowledge my mistake and am willing to pay. What I’m concerned about is the payment methods. I’m uncomfortable giving a company my credit card information so they can charge me weekly without my consent. Additionally, my bank has experienced issues with international payments and cannot process a bank transfer. I’ve asked for multiple payment options since I’m in the US and they are in the UK, but they haven’t provided any alternatives. Now they say they’ll involve debt collectors, which is why I’m asking what will happen while I’m in the US. They haven’t given me any information about their next steps.

She informed you that the petrol you placed in the car was ordinary and that doing so had destroyed it. You ought to compensate them for the financial harm you caused to their car.

They are therefore unable to report you to an American credit agency. You do not have an international credit score. The United Kingdom possesses its own. Thus, if you care, it will mess with your credit score in the UK. They might have a judgment against you from a court in the United Kingdom, but it wouldn’t be enforceable there.
It can make it difficult for you to return in the future. You can safely advise them to screw off if it was a once in a lifetime experience and there is absolutely no possibility that they will ever wish to return.

Thank you. Is a credit score granted exclusively to those who have resided there? I’ve never had a bank card or credit card when traveling to the UK to see my family or SO. I am a US citizen, hence I don’t even live in the UK. I don’t understand why they are requesting my credit card information by email when I’ve never heard of a business doing so.

The story is peculiar. Why wouldn’t you check and just assume what kind of gas is in it? Usually, it has a label on the door.

There, are the pump nozzles not of various sizes? In the United States, a diesel fuel nozzle is larger than a gas fuel nozzle. Had there been a clear warning sign

The conventional sizes of nozzles range greatly. Diesel nozzles are 25mm in diameter, while gasoline nozzles are 21mm.
The story is hardly convincing because of the rental agent’s evasive responses when questioned, the car’s missing fuel sticker, and the pump’s gasoline nozzle used for diesel.