Activation lock. Forgot iCloud username and password

Hello everyone

I have the following problem:

My cousin bought a 128 GB iPhone 14 Pro Max phone on credit for 24 months on one marketplace in the Republic of Kazakhstan.

She set up the iPhone on her own, but later forgot the password code and restored iOS via iTunes according to the instructions.

Now, to activate the iPhone, you need to enter the username and password of the iCloud account.

During the creation of the Apple ID account, she made very critical mistakes:

1. Everything she did was not documented on paper, in the end she does not remember which e-mail she specified when creating an Apple ID account.

We tried to search on the site with her https://iforgot.apple.com/appleid but they didn't find anything.

2. Having no experience setting up an iPhone, I did not turn to experienced users.

What was done:

We contacted Apple Technical Support (3 requests) and described the situation

But we received a refusal because there is not enough evidence about the purchase of a smartphone.

When analyzing the situation, it turned out that my sister made a second critical mistake when buying an iPhone:

1.When buying on credit, she chose a seller on the marketplace who sold a smartphone imported to the Republic of Kazakhstan from Japan.

From the documents we have a bill of lading, which was issued by an individual entrepreneur. But technical support needs a receipt from the place of initial purchase in Japan.

2. I went to the store that sold the iPhone on the marketplace, they can't help with anything, I contacted the marketplace.

If buying a smartphone she chose official suppliers stores Technodom , Sulpak , Alser , there would be a receipt and official support in the Republic of Kazakhstan.

3. I contacted authorized services by phone of Apple Corporation in the Republic of Kazakhstan

They told ALSI and iSpace that they could not help with iCloud blocking problems.

4. I ordered a paid report to find out where the iPhone was bought in Japan, it says it was bought in Apple (but it does not indicate which Apple Store).

Less than a month has passed since the purchase in the Republic of Kazakhstan.

Questions

1. How to legally and honestly prove to Apple technical support staff that we bought a smartphone on credit in the Republic of Kazakhstan and disable activation lock?

2. How to remotely get a duplicate purchase receipt from the Apple Store in Japan for technical support. Going to Japan is economically expensive and far away.

3. How to find out through Apple's technical support what data she indicated in order to try to answer secret questions.

I ask for help since the smartphone was bought on credit, pay for it for two years.

Paid services for unlocking ask from 300 to 400 US dollars.

Considering the purchase on credit , overpayment for it and paid unlocking, it will just be a platinum iPhone 😊

In case of successful recovery of the iPhone, I will do everything so that the sister will reliably document the account data.

Thanks!