Help with billing

[Sophietheblack]

Hello everyone,
Since the roaming details changed, that's my first time abroad. In the EU zone I used to use the O2 travel option before and when I arrived (the same country I'm usually using it at) I automatically set it up and got a confirmation text message that now it's on. Than I got an automatic message from O2, that in the EU zone from now I can use my account just like back in the UK. I had just the basic package with 300mins and 300 mb included. I didn't realized, that ran out already of my minutes allowance, but I was confused anyway that how will this work? Will the O2 travel just automatically switch on when I won't have anything left from my monthly allowances? But nothing like this happened. Actually today I had to face with an everything but pretty "international charges" on my account. I got charged with £18 already, not including the minutes I used today (before I realized,that it cost a fortune for me). So basically with changing the roaming seems, no more saving options after you use your monthly allowances?
But despite all of this, I checked my upgrade options and decided to change for a bigger monthly plan,I'll probably need it anyway. On the website I found an offer, 1000 mins 1gb net unlimited messages for £12/m instead of £16 until 26th July. Ordered it, it's been set up already as well. Perfect. My tiny problem is: on my account says,that it'll cost £16/m for me...so where's the discount? And I checked my allowances and found only 741:56 available minutes. Well, could be counted only from now, not for a full month, acceptable. But if it's like this,why do I have all the 1gb net? So the system already took the minutes I used over my old plan and now I have less minutes but I'll have to pay for them as well?
Just to make it a bit more understandable I can attach a few screenshots from my account.

Thank you for your help in advance!

[jonsie]

Your discount will show a a bolt on (-£4.00) when your bill is produced. It does sound as though you will pay pro rata until your billing date when you will get your full allowances. If it isn't clear, call 202 around 8.30 in the morning for clarification. 

[MI5 · Accepted solution]

If you go over your allowances you get charged the same as at home so your standard rates apply. No more o2 travel for EU zone.
Your discount is applied as a bolt on so the tariff shows at full price but discount is applied when bill is produced.
Your mins are pro rata until the end of your normal billing cycle which won't change so your bills will be on the same day as always and you have 700 odd to use until then.