Bigbasket.com — One particular item was not delivered but i was billed for it

My contact number is [protected]
I have placed 48 orders during last one year. My last order dx - mco[protected].
One particular item was not delivered but i was billed for it. I took the matter with your staff. I was informed that due to excess grammage (In weight) that item costing rs.28.60 was withdrawn to make up for the price difference.
And this i am informed only after i asked for clarification why a product was billed and not delivered. This is recorded in your chat.

If the weight exceeds charge me for it and i would have paid even before your delivery was made.. Where is the transparency in your billing is you randomly don't deliver a product and later inform me that it was adjusted for a weight difference.
I am a regular and so far satisfied customer.. Let this not mar our relationship and make me switch another to another grocery e tailer.
I expect a reply from you.