No Blackberry BIS phones only DATA

I send a mail to MTN on Monday no reply, tried to phone no answer , when I did get through , I had a query why don't you have any Blackberry's with BIS , so no answer on that only that all our Blackberry's use DATA, and not this month, so will you have any Blackberry's using BIS on contract next month on that I had to be transferred to the sales department who did not answer the phone after 15min holding on, whats going on, why is your service so bad and why don't you have phones with BIS are you not making enough money with phones that have BIS, i want to know if they will be available next month so get someone to phone me back, I can't hold on forever.