R18k for services never rendered

Charged R18k for services never rendered by Mellins I. Style spectacles. After consulting and getting a quote of R18k, I app**** for an in house finance, when that was declined due to poor credit history from my side. Mellins went straight into my Medical aid savings to claim the credit. After instructions to my Medical aid to reverse the transaction, I was sent a letter of demand for R18k. Even after sending an affidavit to the effect that I did not receive the spectacles, Mellins still demands payment on the basis that I signed a Quatation.