In the business myself and there is absolutely no excuse for what has happened.
As carpenter suggested, photos and document everything. However you are going to have to prove that the floor was in perfect nic before they started - they could quite easily say you put the card down to cover the damage etc etc. Same with the sink, they'll say it was delivered from showroom like that.
Don't hand over money, but get ready for plenty of abuse and legal threats but stand firm. Quite simply, if it costs less than 3000 to do the work the builder will eventually do it, but if over 3000 he'll cut his losses and run