This is BTWifi help desk number. 0800 022 33 22 Give them a call and explain your problem. They are usually pretty good at sorting them out.
How the BTWifi (formally know as BTFon and BT Openzone) works is like this:
BT Customers who have a BT Home Hub and are opted into the BTWifi(Fon) service share a little percentage of their broadband service for BTWifi customers and people who have paid for BTWifi access to be able to use.
However the BT customer's own connection will get priority over the devices that are using the to their BT Home Hub via BTWifi or BTWifi-with-Fon.
If the BT customer is having an issue with their broadband then it will mean that BTWifi customers may not be able to use that BTWifi Hotspot.
In commercial stores/cafe's such as Starbuck will offer a BTWifi premium service (used to be called BTOpenzone) which will be more reliable than the BTWifi SSIDs transmitted from a BT residential Home Hub.
Hope that makes sense,
If you are not willing to pay for the call then you will need to find a BT landline or BT call box and phone from there.
As you have paid for access to BTWifi contacting the help line is really your only option as it appears that there is something wrong with your access key.
i cant phone the number as it costs from mobile
Try 0330 123 3000, which would be covered by your mobile call time.