No provider of credit utilises your arbitrary credit score to determine whether they should extend you a credit facility.
They use your payment history and employment status. For larger amounts they'll include collateral.
Not every business offering finance is looking to leverage that history in the same way to turn a profit. Some business models actively want those with less than stellar history, believe it or not.
Stop focusing on the credit score. Obtain credit, be it phone bills or whatever, then build on that with credit cards. Never be late with payments. Ever.
In the last 3 months I've utilised $30,000 more of my lines of credit. My credit score went down. Because of my history of never missing a payment and showing lenders I'm borrowing right now I receive multiple offers weekly offering me more credit.