Banking

I took a home loan with fnb which I was paying by debit order from my cheque account. I had to close that cheque account because I had a debit order with a company called DFP since June 2017. On October till February it was showing that the deductions were successful and have the remaining amount in my account as shown on the bank statement. DFP said the money was reversing I logged a query around May 2018, I am still waiting for answer. After closing my cheque account I moved my salary to a saving account. I normally do transfer to pay my home loan as I haven't done the debit order forms. Since May 2018 I noticed that some of my money disappear from my account. I have deduction called "set off" which is unknown to me.