Public Mobile should allow users to exceed posted data limits. If you have 1GB then once you have used up your 1GB you should not simply get cut off. Reduce speed so clients can still do important things when data is required.
When Public Mobile first launched in the old old days they had true unlimited data. No slow downs like other carriers, no hidden maximum use etc. When Telus first bought Public they changed all the old unlimited accounts to maximum data use.
The reason this becomes important is other carriers like Wind, Mobilicity & Chatr all allow users to get access to slower data once their high speed data has been used. Public (& Koodo) are not yet offering this but I think it would be very popular with users.
