Poor customer treatment

On the 28th of January, I ordered the chicken tikka meal from this restaurant. This meal comes with a quarter chicken, a salad, chips and naan bread. The meal was delivered without the bread, this I realised after the delivery guy had left. I called the restaurant to enquire about the bread, I was told that they won't be able to deliver the bread on that day, but to compensate, the next time I order won't have to pay for the meal and that I will get an additional bread as a apology. On the 29th of January I ordered the same meal through Mr Delivery. Once the order was processed, I called the restaurant to make sure that I won't have to pay for the meal. I was assured that they are aware of the issue that occurred the previous day and that the meal would be free of charge. Upon my meal being delivered,the delivery told me that the restaurant did not tell him that the meal would be free and that I have to pay. I immediately called the restaurant to resolve the matter, then suddenly no one wanted to acknowledge the fact that I was promised a free meal. This led to a back and forth between myself, an employee of the restaurant and the owner of the restaurant...This back and forth lasted for about 15 minutes, ending with the owner of the restaurant screaming in my ear through the phone, telling me that I must return the meal. I was so disturbed by what happened to me and completely shocked at how they treated me. I have been buying food from this particular restaurant for some time now, I'm so disgusted