Bath Tub with a crack

I went to buy a bath tub at Builders earlier in the month. It was the last bath tub (Luso) in the shop. It came wrapped in plastic and bubble plastic. Collected and installed at my house. The bath is installed with the plastic still on to prevent scratching. When it was fully installed and plastics removed, upon inspection i discovered that there is nasty crack at the top corner. It is a good 15 cm long. At this stage, I don't know what to do with a fully installed cracked bath tub, which is paid for and also the builders were fully paid for it. Yes, i tried to inform the store about it but i couldn't find my receipts and the store refuses to re-print them even though the transaction was done with a cheque card. Do i demand a new bath + installation fee paid to builders?