Birthday voucher not sent yet

Hi there. I just bought a house and I need 2 aircons for my home.i called builders and they said I get a 10 percent voucher for my birthday month and I have not received that I went into the store and no one knows nothing about it.my birthday was on the 18th of November and now this Saturday is month end how will I be able to get that voucher and I need to use it by Saturday that doesn't make sense because if I don't get the voucher I loose out on that discount and I need it as well.builders is a big company they need to train their staff to know all these things if they want busy