Poor Service of SAMSUNG

On the 30th January 2018 I handed my Samsung Galaxy S7 Edge phone in at SAMSUNG in The Groove Mall in Pretoria. The technician told me that the motherboard and battery is damaged and needs to be replaced. They assured me that it will be 7 to 14 days for the repair work to be done. After 14 days I phoned them where they told me they are awaiting ETA of the spares. After numerous phone calls to the Samsung Service center and Samsung head office they said it will be fixed as soon as possible they are waiting for spares. They could not answer me when I ask why they don't replace the device if they do not have spares. On the 8 March 2018 at 17:28 I received a SMS that the repair work on my phone was completed and it can be collected. I made arrangements for my device to be collected for I am staying 410km from Pretoria. On arrival my sister was informed that they are still busy with the repair work. I spoke to Khabelo who assured me the device will be ready Monday 12 March 2018. When I phoned them on Monday, I was informed that they are still busy and will hopefully be finished by Tuesday 13 March 2018. Is this really service from such a big company in South Africa? If they don't have spares why don't they replace devices? Instead they are making promises that they can not keep.