Unable to use International data in UK

I have purchased T-Mobile 7 days 50MB Domestic Roaming Pass to use in London UK but I am unable to use it. 

I have confirmed: 

• Mobile Data is turned on.
• Roaming is turned on.
• Rebooted few times after activation. 

None of it is helping and keep seeing little "r" with "!" on the notification top right bar. Live chat thru T-Mobile hasn't been the best and hoping if someone has recently traveled to UK and has been able to use this pass. 

Thank you in advance,