You didn't buy the EE 10gb sim with £15 call credit did you?
I have been going through excruciating contortions of getting an account to fully activate all my details (and email link) via website, app, customer support, Amazon supplier Chitter Chatter, 150 not putting you through etc etc.
Conflicting instructions from so many sides are so hysterical it's hilarious.
It sounds like you have a different plan, but EE's systems are shot to hell. I too still get a H or 4G indicator but cannot connect to other than EE.
If you have the same plan, you would run out of a 50mb data start up and never be put on the full 10gb after having your details entered.
Shame as it has much stronger data and call quality than on my other phone, a Note 3 on Three's one month unlimited plan, so I wanted to switch both phones.
Just venting my spleen, you may have a different problem.
The possible issue may be faulty sims from a third party. I would ask for a new sim in a store if it persists. They only take 30 minutes or so to activate.
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