Guarantee repairs not able to do.

I bought a Tata Super ACE EX2 bakkie in August 2015. This year February 2016 I discovered a oil leak on the motor. The vehicle was booked for an assessment on the 16 February 2016. The report was that the sump gasket was leaking. They told me that they don't have stock of the gasket, but will contact me as soon as it arrives. On the 25 of February we phoned and they said they will comeback to me. We phoned this morning 7 March to find out why they are not coming back to use. I was told that she doesn't have the gasket yet and don't know when it will be in. This is totally unacceptable!!