Swiggy Bundl Technologies Pvt Ltd - Charged Extra so asked to cancel whole bill amount is added as Cancellation fee in my account

Ordered worth ₹*** with offer applied,after placing order again added extra items through customer care worth ₹**, but I received message saying "you have pay extra ₹*** for extra added item" then immediately contacted customer care they said my mistake you received message that you have pay ₹***,then he said now you have to pay only ₹**,but delivery person demanding to pay ₹***,since he is demanding more money I told to cancel the order, and order has been cancelled but, Swiggy has added full order value i.e ***+*** =₹*** as cancellation fee in my Swiggy account, no resolution is provided by Swiggy till now, just saying "feel bad that you are going through this. Trust me, this doesn't happen often. We'll do our best to ensure you only get the best experience with Swiggy going further."