Money making scheme

On the 15th f March one consultant phned me regarding the outstanding balance on my account, I made an arrangement for R500 to be debited from my account on the 24th of March since the 25th was a public holiday. On the 24th R500 was debited as per arrangement, on 29th of March I get another call from them saying they did not recieve payment, told them that the money was definately debited. What makes me mad is they charge you almost R30.00 for phone call, I find it unfair that they charged me that amount and yet my account was paid, Why didnt they wait until month end to see if the money is reflecting on their account?The very same lady who phoned me that day she told me I wont be charged for that phone call, I then requested them to email me the statement and that phone call fee was reflecting on the statement, I phoned them again and I was promissed that it will be taken off, requested thm to email me the statement after is taken off, I havent heard anything from them. First I was charged R36.00 for letter of demand which was apparently posted to me & even today I swear I haven't recieved that letter.I want to pay this acc finished but they are making it impossible for me.