Lemon Tree Hotel - Incorrect Billing and over charged

Hello,

I have been a very loyal customer to "Lemon Tree Hotels" and have made bookings with them many times.
I have been booking the presidential suits of the lemon tree hotels from last two years and this time i was shocked with what i had to face.
I contacted the head of sales department and we discussed my requirement and the person offered me a quote of Rs.***** + **% taxes.. later after discussions and recommendation from another manager of a different branch the price was settled at Rs.***** + **% taxes on condition that i come down to the hotel and pay a booking amount. My bad was I dint have this mentioned price of Rs.***** on the official mail threads which were going on.
The booking was for December **,**** to January **, ****.

On the time of checking the hotel front desk informed me I need to pay a pending on Rs.***** ( I had already paid Rs.***** as advance booking payment ) I said i will discuss the same with the sales manager and get back.
I called the manager and he said he doesn't remember the price we have finalized and said he needs time to check on it . After constant following up with him he denied that he has given me the Rs.***** price tag.
I had to accept this as i did not have the mentioned price any where mentioned on the email threads, it was on a phone call.
All this was happening at **pm in the night. I went down to make the bill payment at the reception and the person over there swiped my card for Rs.***** and just handed me the card swipe receipt and informed he cant provide me a bill.
I was in a hurry to go back to my friends as it was almost ** and dint wanted to miss the New Year celebration and dint even check the swipe receipt.
Later when I contacted the sales manager regarding the higher amount being charged, he informed me that they have added extra **% on the total as a charity and welfare of the physically challenged people employed at the hotel.
I was shocked to listen to that as no one informed me about that component in the bill.
He told me that the same is charged to all the guest of the hotel and he agreed that they do not inform about the same to the customer!! The customer has to check the printed bill to check the **% component and inform the reception to remove it as it is not compulsory to contribute.
So charging customers without informing them is like cheating them!!!
Getting back to my case, I was not issued a bill to even check what i was being charged!!!
The duty of the staff is to staple the swipe receipt and provide a printed bill!!!
The manager informed me that nothing can be done and he was proud to say that they do this to all customers!!! and will not be able to refund me in any way.. after requesting him about it he said he will give me a discount on my birthday!!
I am attaching the conversation I had with the manager on whatsapp where he clearly accepted that they are charging all the customers without informing them and also accepted the fact that I was not issued a bill!!
I am looking forward to file a consumer case against the hotel and the manager to seek justice and the humiliation i faced talking and dealing with them.