Problems when shifting gears

On the 6 November 2023 took my Isuzu in for a problem when changing gears. I was told the gearbox need replacement and will take 2 weeks under warrantee. 2 weeks later and i was informed it was the wrong gearbox that arrived. One week later, they received new a second gearbox and the gearbox were fitted. I advised via telecon to Motus Isando it was still giving me the same problem. I was told to drive the vehicle for a couple of days because it had a new gearbox and clutch fitted. Vehicle is back at Motus Isando and i am waiting once again for the problem to be sorted We are a month in, and still this problem is not resolved.