Utter disppointment !! Paint Colours and Codes Cannot Match??

I had purchased Fired Earth - Severe Weather - Lightning 20litre in 2019 where we painted accents on a flat we had built on our house. In January 2022 we wanted to start painting our house the same colour and accents as the flat, and purchased a 5ltr of the same paint. This shade of grey was extensively lighter than the previous 20ltr container. When I approached the paint specialist at our Builders warehouse in Rustenburg, with samples and even a paint brush where I demonstrated the difference. He said to me that not one batch will be the same as another of the same brand and paint colour, especially two years different. I am not a specialist but have dealt with out company maintenance and I restore old cars as a hobby, a paint code match is to be the same in every batch even is 10years later. I mentioned this to him and he shrugged me off and said contact the supplier, as their batches do not and will never match.

How do i spend thousands of rands on painting an addition to our house, and when I want to paint my original house the same colour, the same paint brand/range and colour will not ,match?? I have already wasted money on the 5ltr, so now do I have to paint the entire house and flat over wiht a new paint range and colour?? This is ridiculous.