You do not get what you pay for as per menu

At Compadre Portuguese grill Honey Crest center on Beyers Naude which I have been there many times but tonight I ordered a Espetada Rump 350grm and I could clearly see it was not close to this weight. When I questioned the weight I was told the manager Gareth Higgins said via the waiter they receive it as is from supplier. The waiter then brought us the packed Rump and the weight was just over 300gms touching on 315gms. When I requested to then reduce the price it was said no as it arrives from supplier and that's it. ( I was told the manager was not negotiable ) It was mentioned this is the norm. We did not even finish up as we could not get what we paid for. We left and will never return again. The manager throughout everything stayed in the kitchen. A good manager would have come to resolve the matter, On the slip it was recorded as a 400gms yet they couldn't even give me a 350gms. You do not get what you pay for. And it seems the General manager does not interact with clients but chooses to hide in the kitchen as per our experience tonight.