Allmerc Spares, Pretoria Gardens don't understand cust

I bought a few thousand rands of used parts in December 2018 and January 2019. One incorrect part was delivered and returned by their couriers. Allmerc Spares, their admin person "Bianca" communicated with me to settle my refund. Dozens of calls and emails to her and six months later my refund amount is not settled....lies upon lies.. sinc March, their refund form was completed and send back to them in all their formats and they claim that they are still waiting the right format. The worst business to deal with.