on 23-11-2017 06:24
OnePlus 6 (O2 & Sfr), Z3 Tablet (Three UK), iPhone 8+ (EE)
on 23-11-2017 06:54
The number is not one I gave in the ways to pay guidelines. It is a legitimate O2 number though @Toby said this, when we queried it
"If anyone ever has any outstanding amount, you should always call 2729 from your mobile or ring or 0800 588 4217 from a landline and enter the mobile number you wish to pay for".
Always better use the Ways to pay guidelines shown in the post above