Dissapointed

Good day Can someone please explain to me something regarding my service. First of all i made upfront cash payment of R7400 in December for major service. My car was serviced on friday. Parts of R4945 was inserted in my car. The lady told me if i was going to make a paymemt on friday i was going to pay R8000 i just need to know why R8000 while i was qouted for R4945. All i want is an explanation please. And where my balance of R2400 went. Please. *** can also contact me here. Thank you