Swiggy — I am complaining about my order

I ordered some combo from madurai idly hotel and it has been accepted and confirmed. While i waiting for my order, i recieved a call saying that the item i ordered is not available and i am suggested to pick some other item. First of all, they should not have picked my order if item is not available. Secondly, if it is not available, immediately they should have informed me instead of informing me after half an hour. Thirdly, after some time i am asked to cancel my order. Why should i cancel my order when it is the hotel who confirmed the order and then later says item is not available?