Frustrated nissan owner

I have not seen such poor service from car dealer. My nissan navara that i bought new had problem with the diff,they said that they're going to replace it but even second diff was faulty. The problem was reported in feb 2020 so my bakkie went in for repairs march 2020 and still to this present time my bakkie is not fixed,they said that there was new parts to arrive at 12 august eta,still no parts have arrived its been six months. There were my bakkie is held, I don't know if its been look after or is it standing in the sun the hole day maybe rats have started eating at electrical wires. The after sales is absolutely dreadful.