Absa homeloan system debiting error

Absa homeloan keep calling me about a debit order which is R4 (four rands) short of what it should be. I have a homeloan with ABSA and given me a mandate to debit my account the 15th of every month which they are doing. All of the sudden am told the system is having a fault and debiting 4 Rands short, is it my fault, why can't absa fix their system? Is it *****, because I can't be showered with calls like this from a bank of reputation. Absa must just manage their system and stop making it my problem or anyone else. It's boring, we live in a vulnerable world and don't know what to trust anymore. All of the sudden my debit order is canceled and a new mandate is requested, should I accept it, honestly that's how ********** activities happen. Just reinstate my debit order as agreed, I've not experienced a mess like this before