I don't get it, apparently I'm not good enough for the finance of BNPL (6months)

I'm a student with a £1250 over-draft, working 20hours a week with enough money to pay back (living under parents roof).
Getting rejected for this feels as bad as a rejection during a night out
Unfortunately not all applicants make it through the very tough criteria - from our perspective we wouldn't wish to put anyone into debt that cannot afford to get out of it equally we'd like as many people as possible to enjoy the benefits of deferred payment.
Here's an section from the Finance T&Cs on our site;
If you decline my application, what is the reason?
In addition to credit scoring, we also take into account confirmation of your identity, validation of certain application details, existing commitments and information held at the credit reference agencies. Though we are unable to provide you with a main reason for decline of your application, it is usually based on one, or a combination of the following:
Your credit score (note that every finance company will score you differently
Adverse credit reference agency information
You are considered to be overcommitted
You are aged under 18
Your existing account performance with other lenders
What type of information do credit reference agencies hold about me?
Some of the information is public information, for example electoral roll, County Court Judgements and bankruptcies. Other lenders may also file information about accounts you hold with them for instance this could include your payment history and outstanding balance on these accounts. Any requests for credit, where a credit reference search has been undertaken, will also be filed, although the result of the request is not recorded.
How do I obtain a copy of this information?
You should send a cheque for £2, made payable to the relevant company, together with details of all addresses at which you have lived over the last 6 years:
Consumer Help Desk Experian Limited PO Box 8000 Nottingham NG1 5GX
or
Equifax Department 1E PO Box 3001 Glasgow G81 2DT
You can also find out more about credit decisions by visiting the above companies' websites:
http://www.experian.co.uk/ and
http://www.equifax.co.uk/
The above listed agencies will provide details of information relating via these addresses. If you believe that the information is incorrect, you can ask the agency to correct it.