Declined (general system error) transaction debited against my bank account

I made a purchase at a vendor using an iKhokha machine. The first transaction was declined (general system error), I then performed another transaction which was successful. The day afterwards I noted that there were 2 transactions from the merchant pending on my bank account. I immediately emailed the vendor who contacted iKhokha who indicated that only one transaction would go through. Nevertheless both transactions went through. I again contacted the vendor. All of these attempts to get the declined transaction reversed failed and I had to log a dispute with my bank. A total waste of my time. Be very careful of iKhokha transactions!