Bundle vs. PAYG question

[jamjam]

Dear All,

I have tried to search for the answer, but I was confused by the terminology.

I was wondering if I could have a SIM card and directly use my left credit without opting in any bundle or rolling plan?

I got a new SIM card, but after I topped up 10 pounds, it automatically changed my credit to a 10 pounds bundle (although I got a 10-pound credit later by using the FREE10 code).

Currently, it will still change the credit to the 10 pounds bundle next month, but I just want a "REAL" PAYG SIM card to use my left credit. 

Thanks.

[MI5]

@jamjam 

O2 no longer offer "real" PAYG.

You need to look at giffgaff, Tesco Mobile or 1pMobile as they are the only ones left offering it for now.