not able to call mtn network

i had 3 contacts with them where since last year i cant make any calls to mtn! i reported it then it is fix and then it happened again the i had to wait weeks before they fix it again..so canceled the contacts,hoping it will change now when i go over to prepaid - 01/05/2021 i bought the sim cards and the 04/05/2021 it happend again where i can't make calls to mtn this now the 19/05/2021 and still not answer '' will escalate the matter'' is all they know what to say!!! case numbers *** *** SN***