MTN think they are very clever to fool people with their nice talks

i was for a very long time with MTN and i had no troubles with them. i always pay my account and i always pay a little bit more, for instance if my account shows R825 i will pay R 830 or R840. now in June i made an arrangement with MTN to make payment end of July as i did not had the funds to make payment end of June. they accepted the agreement. my normal contract is between R 840 - R890, it differs every month with some R5 or R15 or so. not that much of a deal as its below R900.00. i received my statement of June which was R880.00 something, and by end of July i had not received any statement so then i went with R900 + R900 (for the month of June and July) and i went to pay R 1 800.00 on my account. when i got at the store the guy told me that my account is over R 2 000.00. which was a shock as that can not be right, so i called MTN (after they suspended my lines which is still not activated till now) and the lady told me that one of my lines where migrated with a device which makes it R418 and not R226 (what i always pay). then i remembered that MTN called me on the 28th of May 2020 claiming that i was paying too much and that they would like to migrate me to a cheaper contract, so instead of paying R226 i will pay R169. and i explained to the lady that if it will only be R 169 then it is fine as i dont have the money to pay more. then she explained to me that i am only migrating from one package to another without a device so i will only pay for the data. and i accepted. so that lady that assisted me did not do her job as my account for that number is R418 and not R169 which was agreed on, now i have to pay that extra amount of money which i dont have because of someone who didnt understand, or didnt know or what ever the excuse is. that is unacceptable. still my lines are disconnected because i did not make an arrangement or pay the outstanding amount. i WILL not pay that amount. MTN can block my number, hand me over, do whatever they want like they always do, but they will not get one single cent out of me unless my line is fixed and that fee is the amount to which was agreed on the 28/05/2020.