Lamb Meat is hard and chewy

I bought half lamb yesterday and I cooked some today 17/07/024, I phoned Giant Hyper immediately and I was put through to the butchery manager he told me that only way he can help me he send it back to the Abattoir they will check to see if it is lamb or not and he said they must reimburse, and I complained this is not lamb God knows what meat is this, I cooked it for 3 hours it's hard and chewy the colour of my curry doesn't seem right. The butcher by the name of George that helped me when I went and bought this meat he **** I asked him several times he said I guarantee you this is lamb, so with this Giant Hyper they don't accept returns even if the customer is not happy. I am a pensioner and to rob someone is not right. Things are so expensive and we as customers support their business by yet we are treated so bad.