Being charged for evening phone calls on Evenings and weekend product

[#1]

I have just received an email saying that i am near my credit limit. On investigation I find that I have been charged more than £40 so far this period for calls, all of these calls have been made after 1800 and should be included in my package.
On further investigation I notice that this has been happening for many months even though this is the first time I have received any notification,
How do I get this sorted out and obtain a refund for wrongly charged calls,

[#2]

Calls should be made at 7pm and after in the week ( anytime at weekend) for no charge to be applied, up to 60 mins, then redial

Quote from: http

Inclusive calls to UK landlines, 0845 and 0870* numbers 7pm and 7am Mon-Fri, any time on Saturday and Sunday

Kind regards
Mike