Unauthorized Set off

There was a second amount taken out of my savings account by Standard Bank - Specialized Collection Department apparently for payment towards a loan of 2006. I have not been working last year, i have just found employment that offers a very minimum wage, i am a heart patient as well. Firstly an amount of R813 was deducted from my account when i got paid this month. therefore my medical aid had been unpaid due to not enough money been in the account. i was waiting for SARS to pay me my rebate in order to catch up with my arrears as well as to provide food for my family. They did so yesterday 13/08/2015. so i transferred the amount to my other savings account as i would do my payments on Saturday 15/08/2015. This morning i receive a sms that R2386.27 was transferred to the same account , which is a set off by the bank. I have not received any statements in this regard or even a payment arrangement was never done. i am highly stressed as i need to go for my check up, pay my medical aid, my arrears on my rent, plus buy food to eat and i need money to travel to work till month end. I have spoken to Edward Ngathi from the department, he is not helpful at all. i Need it refunded pls.