Fix my account

What a very *********** service MTN agents including their Team leader, I was called earlier in the month and was advised my premium was not received for the month of JUNE, this was their issue not that there was no funds in my account . Ok we make arrangements with agent that they should double debit now end of July, she sent me another Debi check mandate I approved and we agreed 2 premiums will go off R2600 the 1 missed and the 1 that’s due now in July. This morning I wake up to a text I must pay R4000+ and should be a cash payment, now I’m confused as our arrangement was not like that . I call MTN to get answers as to what is happening, was transferred to a very RUDE Agent called Poppy and still does not give me solution where to from here. All she says in a very demeaning tone wait for 31st to see. I can not wait because I am disputing the 4k and I can’t afford 3 payments while I’m due for 2 and it’s 2 not because it’s my error… the team leader tried to assist but is just as clueless like the agent. Can I get a solution to my issue before debit date. ***