Poor consultant service

Hi,i wanted to purchase a mifi LTE/3G pocket router at telkom rosebank and was told they don't have stock and said alternatively the telkom cresta does have stock.When i get to cresta there's no stock of the router for R599 and then im told i need to Ric a sim card? Please tell me if i do purchase this router(R999 LTE router) can i use a Cell C sim card in it instead of the telkom sim? please advise...thanks.