Shoppers won't get any undelivered items from JJB Sports bought before this week, and they won't be able to return items or use old gift cards after the retailer's collapse.
However, customers may be able to get compensation from their card company.
Rival retailer Sports Direct bought 20 JJB Sports stores, the brand and its website this week, while the remaining 133 shops were closed after JJB Sports went into administration on Monday.
Sports Direct says the 20 JJB Sports stores it has bought (see the list) are still trading, although they will eventually be rebranded under its own name.
The JJB Sports website, which was down earlier in the week, is now trading as normal under Sports Direct ownership.
The key date is Monday 1 October. Any orders from that day appear secure. The problems are for customers who bought anything before Monday.
Important note: As things stand, JJB Sports' administrator, KPMG, says the information on getting money back in this article applies to JJB across the board, even parts of the business purchased by Sports Direct.
We are awaiting confirmation from Sports Direct whether it will wash its hands of JJB business from before 1 October, or come to affected customers' rescue where it can.
Orders won't be delivered
The administrator says it won't be able to deliver unfulfilled online orders placed before 1 October.
Instead, contact your credit card provider first to get a refund under Section 75 of the Consumer Credit Act, if the item is over £100. For full help on making a claim, see our Section 75 refunds guide.
Or try the Visa or Mastercard chargeback schemes if the item cost less, or you paid by debit card.
The chargeback schemes are, however, a customer service promise rather than a legal requirement, so there's no guarantee of success. For more help on making a claim, take a look at our Visa/Mastercard chargeback guide.
If you don't get anywhere via one of these schemes or you paid another way, you'll have to try to claim the cash from the administrator by writing a covering letter and sending it with a copy of the receipt to Sarah Dunwell, KPMG LLP, 1 The Embankment, Neville Street, Leeds LS1 4DW.
Don't get your hopes up of getting all your money back via this method, as it rarely happens.
Can you get a refund?
JJB's administrator won't issue any refunds on faulty or unwanted goods bought before 1 October.
If you bought something that cost £100 or more by credit card, contact your card firm to get a refund under Section 75 of the Consumer Credit Act, if the item is faulty or not as described. Or try the Visa and Mastercard chargeback schemes.
You won't get a refund if you simply change your mind and no longer want the item.
If you paid another way, you can claim for faulty goods via the administrator (using the address above) and become a creditor, though it's highly unlikely you'll get all your money back.
Gift cards invalid
KPMG says gift cards bought before 1 October will no longer be honoured and consumers won't get any immediate refunds.
Instead, unredeemed gift cards or vouchers will be classed as an 'unsecured claim' and you'll have to try to get your money back from the administrator. From past experience, this is unlikely to work.
It's unclear whether or not you can claim for gift cards from your credit card provider under Section 75, as there's no definitive rule.
MoneySavingExpert.com creator, Martin Lewis, says: "You may be able to get the money back for gift cards via Section 75, provided the gift card was bought directly from the retailer and not a third party.
"But it's a relatively grey area as to whether or not gift cards are covered. Currently, there is a very strong case that if you bought it directly from a store and it was £100 or more, then you should get your money back via Section 75 if the retailer goes into administration.
"However, as it's an untested area, it may be that you are rejected straight away by your card company, in which case I'd recommend you go to the Financial Ombudsman Service. See the Section 75 refunds guide for more."
Also try the Visa and Mastercard chargeback schemes for lower value cards and vouchers, though there's no guarantee this will work.
We urged shoppers to use JJB Sports gift cards last week while they were still able to (see the JJB warning MSE News story).