Haven't received trade-in kit

Apple promised to send Trade-In Kit with mailing label to return my MacAir trade-in. Kit not received.

Help. If I don't return trade-in within 14 days, I will be charged for the trade-in value against my new purchase. I've tried contacting Apple using numerous channels with no luck and once was referred to wrong number. If I mail it to an Apple store, will they process my trade-in? I can't get Apple store to answer the phone to ask. Any ideas?