Bad service for repair

On Sunday evening 17th April my Samsung S6 switched off, it would not switch on again. On Monday morning first thing I took my phone to the Vodacom shop at Mall @ Reds in Centurion. They could not assist me and said my phone had to be sent in for repair. On Friday morning the 22nd of April I received a SMS with job nr ***8 and an amount of R2174.57. No quote with descriptions on what I would have to pay for. I phoned the number on the SMS and they said to me that the battery is faulty and I need a new battery. I asked the lady to send me the quote via email so I can see what I am paying for. The quote via email does not state how much the battery is but I must also pay for a new back glass and a new rear unit. I don't understand this as my warranty booklet states that care must be taken to open the rear side to get to the battery and that the glue must be heated to correctly open it. I rep**** on the email from Annamarie Williams twice asking why I must pay for the extra back glass and rear unit as it is only my battery that needs replacing. She did not reply and I am still awaiting a response. I really feel that this is not fair to pay for the back glass and rear unit if it was not properly opened.