how can one screw up a wedding reception like this

We had a meeting with one of the managers steve at the branch(Monday) me and my fiance made a booking to have our wedding reception there. in the meeting it was clearly stated from steve that we just had to promise 40 people to be there and that we could order of the menu. The following day the owner contacted us to say we have to order of a party menu that they have witch was already not as per agreement long story short we already got all our rsvps in order based on the information steve supplied now we have to change because your staff makes promises they cant keep to. I want to have answers today this has cause us stress now unnecessary pressure and we getting married the 5th of feb i dont think my fiance needs this either if you do the math 40 people average of 500 per person its 20k and that's still bear min. You cant make us promises and say that everything will be sorted the table seating and the food and venue and we dont need to stress and now what everything is gone too dust thanks to steve and his cleaver promises and dare call me and my wife liars this is what steve said