I called for 20ml vials, and was told they have 15 on hand

I called for 20ml vials, and was told they have 15 on hand. I sent someone to collect and pay this person to go and get it. R200 I already paid R200 to take me to the Kenilworth one which they didn't have in stock. They called me to say they don't have 15 the system is wrong. They apologised and gave me a 5% discount which doesn't even cover the R400 I paid for petrol. I am disgusted and disappointed