"Previously I was with Orange. They are now EE for 'Everything Everywhere'" not quite...
Pay as you go customers (Orange) still have to purchase top-ups by requesting Orange. Orange top-ups are 12 digit numbers to top up. EE is a 16 digit top up code.
The two companies are still separate although one imagines they have amalgamated. For example, Orange still support the old fsmail dot com.
It's all very confusing.