When I try to add my number to my account it says that the number is attached to a different account. I also am unable to add the number to the home plan for T-Mobile since I am living with someone who has a mobile subscription and home internet as well.
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Hello
Do you want to add your number to the T-Mobile home plan for klantvoordeel?
Your registered address should be the same as the address for the T-Mobile home plan.
And have you had an account before for your number?
I want to add my number into the “My T-Mobile” account. I think we have already set up the klantvoordeel. And yes I already had an account, I had the number using a PrePaid sim at first and then switched it to a regular Go subscription recently. When I switched subscription it stopped showing up in my account.
A moderator should solve this for you 
I've had the same issue and something needed to be done on the side of T-Mobile.
Hi
I can help you with your request. Can send me a private message with your 06-number, name, birth-date, address and the last 4 numbers of your IBAN? I believe your old PrePaid account is still attached to your number and therefore you can’t create a new account. I will remove the old account in order for you to create a new one.
Looking forward to your message!
Reageer
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