Whitcoulls, Bennetts and Borders bookstores are not honouring the face value of vouchers, as an administrator stepped in to run the troubled chains.
The Australian company which owns the chains, as well as Bennetts bookstores, is in voluntary administration.
Several customers have told Radio New Zealand their vouchers have not been honoured.
Christchurch woman Adrienne Faherty says she tried to spend a $65 Whitcoulls voucher on Friday morning, but was told she could only use it if she spent double its face value.
She says it's a slap in the face to ask customers to spend more money when they've already spent money on the vouchers in the first place.
The administrator, Ferrier Hodgson, says consumers have other options - holding onto their vouchers until the administration is over or listing themselves as an unsecured creditors.
A spokesperson for Ferrier Hodgson says it will talk to creditors next month about whether to wind up the company or attempt to keep it running.
Redeem asap - consumer advocate
Consumer NZ is advising people to redeem vouchers as soon as possible.
Deputy chief executive David Naulls told Checkpoint he believes the booksellers are able to refuse to redeem the vouchers as, effectively, their assets are frozen.
Mr Naulls says it's a confusing situation but it seems Whitcoulls and Borders are now offering to redeem vouchers for customers who also purchase products of equal value.
He says people should not wait to see what happens with the stores because their assets, not their liabilities, are bought if they get taken over.
Jobs in jeopardy
About 1400 New Zealand jobs are at risk.
Whitcoulls, Borders and Bennetts bookstores are all owned by Australian company REDgroup Retail, which was put under administration on Thursday by its owner Pacific Equity Partners.
Voluntary administration differs from receivership in that it works to benefit the whole company, not just the creditors.
Together the three chains represent about a quarter of all bookshops in New Zealand, including 65 Whitcoulls and five Borders stores.
The chains operate about 260 stores and employ 2500 staff in New Zealand, Australia and Singapore.
Whitcoulls, which began as Whitcombe & Tombs in 1882, is New Zealand's oldest book retailer.