I'll keep this idea simple so as not to dilute what i'm trying to say:
When people raise an issue with agents, there should be some way to draw attention to issues that are taking an excessive amount of time to resolve, or those that are very high priority.
I think a good way to do this would be to add an "emergency button" to the ask an agent section, something that once activated allows the staff at giffgaff to know that this specific issue is taking longer than it should to resolve, or is of very high priority to the end user.
Such a button could be invisible until a certain deadline has passed, say 5 days, then once it is active and pressed by the customer, it could place the issues into a seperate queue in the agents systems, so that they are aware that these specific issues are high priority and need dealing with.
This could replace what people are used to when dealing with call centre based companies.... many companies know call centres don't speed up issues being resolved, but give customers the sense that they know their issue is being dealt with. Obviously we don't have that with giffgaff... and I think this creates a sense of unease for people with issues taking long times to resolve.
Just to clarify this "emergency button" would not be on the forums, but it would be part of the system for issues raised with agents... that customers can click on once a certain amount of time has passed.