No Billing on time nor any help available

MTN has really bad service.... We do not recieve our billing every month so have to physically find out via phone, last month we were told its 1300 aprox so we paid 1500 to MTN suddenly im hit with a bill of 1864 from nowhere and before getting notice my line is disconnected, now this is in lock down and i must do business from Home, but my business line is down.... with no warning, they send me a 24 hr notice sms after they cut my line...and i dont agree with whats outstanding but with no statement how can i query anything????? You phone the 135 line to get assistance with account but only get a message when you press 1 that that option is not correct????