This is a suggestion based on how TekSavvy handles support on the site DSL forums. They have two separate boards there, one for general discussion (and potential user support) and a private board for support given by the company.
Would Public Mobile be willing to set something like this up? The support forum would be a private board were users would post enough information to validate there account (or post from their Public Mobile account). Public Mobile could then deal with these posts directly instead of constantly monitoring the general discussions for posts that require assistance or posts that specifically mention moderators.
As a followup to this I would recommend having a person on that forum 24 hours a day such that when people lose service they can have that service restored as soon as possible.
It is very inconvenient to lose service and have to potentially wait a day for someone to restore that service.
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As per some comments below I would like to specify that this should only be for account related issues.