You could be right and it may be a mistake but there are number of factors that may add up to this total, To name few
1- Koodo charge on outstanding balance 2% compounded monthly (26.82% per annum). That is a penalizing charge which may add up quickly.
2- Tab charges per month
3- GST/PST add up if your figures are net.
4- Any monthly add on, overage & roaming charges
Review your bill closely and if you rule these out then give customer care a call