Phone under warranty but faulty

A Samsung Galaxy J1 was purchased on the 29 May 2015 at Vodacom in Vryburg , on three occasions since it has been taken to the store as the microphone was faulty. Since its last time taken there the software on it has been modified it does not show up the spell check option when typing out messages. The job number on it is ***5 It has been taken to Bloemfontein twice and to the advanced centre in Johannesburg. This has been very distressful and I am not pleased with the level of service I have been experiencing from one of the store assistants at Vryburg Vodacom. The store assistant has been very rude towards me on occasion , when I expressed my dissatisfaction on the quality of the handset.