Carnival Cinema — collected mandatory charges for snacks

I have booked 2 tickets via bookmyshow for movie jalsaghar for 12.5.2019. Ticket charges was rs, 180.00 per person but while booking they collected rs. 100 per person for snacks which was mandatory for booking and when i approached counter person she said this amount will be deducted if you buy something from canteen.
Can any theater make mandatory to pay advance none refundable amount from customer?