Charges over my smart cap?

[#1]

I have exceeded the data allowance on my account and as such realise I will then eat into my smart cap, this is set at £5 but I see excess data charges equalling £13 in my bill. How is this when the cap is £5 ? 

[#2]

Hi daveyp1972!

Thanks for getting in touch with us! If you could send me a private message, I'll be able to access your account and take a look into this for you.

- Rebeka 

[#3]

Hi If possible would you advise us with the explanation that PlusNet give as I think quite a few people are very interested as it may happen to them.

Thanks 

[#4]

Hi 8BKA!

Thanks for getting in touch with us!

If there is a generic reason as to why this has occurred, I'll be sure to let you know however, if this is account specific, I'm afraid I'll be unable to advise you of this due to Data Protection. 

- Rebeka