my card keeps being declined by O2 for top ups despite there being no problems with it

[sindy]

For the past week I have been trying to top up my phone and the card is declined despite my bank confirming that there is no problem with it.Customer services unhelpful but one agent suggesting it may be something to do with ID?Also told to visit an O2 shop but the nearest is approximately 40 miles away.Has anyone else had this problem

[Cleoriff]

@sindy 

All ways to top up here Guide How to Top Up (PAYG) 

If you need further help, call 4445.