Replacement of car Tyres unjustified

In February my husband and I returned to South Africa for a holiday from Malaysia. We booked a hire car online from Europcar paying with a credit card, and collected it in Cape Town. The following day we noticed the rear tyre was slightly flat so pumped it up. A few days later we noticed it was slightly flat again. On changing the tyre we saw the valve had a slight leak. <br> In Durban at our drop off point we noticed a small tack in the rear wheel. It had not penetrated the tyre as the tyre was not flat . <br> On 10th march I received a bill for R1783.99 with codes on the statement that I asked to be verified to ascertain what repair had been done<br> My third query had still not been answered, when the full amount of R1783.99 was deducted from my credit card<br> It then transpires that I have paid for two new tyres to replace perfectly good ones - one of which had a tack, that if leaking (and I doubt it) could have been repaired and the other, a leaking valve that could also have been repaired. My guess is that there is a **** going on there and the new tyres are booked out but conveniently go to a staff member. There is no way those tyres needed replacement.