It shouldn’t take more than six weeks or so for a check to arrive. If you’ve been waiting longer than that, call the company’s customer-service number for the rebate department, which is usually printed on the offer form. Mention the terms of the agreement and the date you mailed the rebate. If you no longer have a copy of the form, try Googling the brand name and “rebate” to find a phone number, suggests Kelley Long. It’s a bit of a long shot, but you may be able to receive your money simply by providing the purchase date and the product’s model name and serial number to the customer-service agent. With future rebates, take these preemptive measures: Make copies of all the required documents, use certified mail to submit it, and read the fine print carefully to make sure you really qualify for that cash-back offer.