Phone sent to 3rd party without my knowledge

I took my Galaxy S4 in for repairs at the Johannesburg smart care centre in Roodepoort. They sent me a quote and damage report which i accepted. Today I got a call from a 3rd party company saying that my phone is with them and that the charge is R1500. I have no idea who this company is and have no idea why they have my phone. I accepted a quote from Samsung Care Centre expecting a repair to be made under their quality standards and repair warranty. I do not understand why my phone was transferred and why i need to now deal with and pay an unknown 3rd party. I also find it strange that the care centres quote had 3 more parts on the repair list than the 3rd party.<br> <br> Please explain why my phone was sent to some random company without informing me.<br> My repair reference at the care centre is ***<br>