Suspended? Fired ? Employer refuses to say.

My son was suspended by a major grocer after years of employment & soon after promotion and transfer to another store.He bought a package of an out of code product that was properly marked and discounted by his mgr. The next day he was suspended for 5 days; he's now being told he will be terminated. He was forced to sign a paper saying he wouldn't buy out of code products AFTER he was brought to the mgr.'s office and informed this was not legal. He has attempted to contact his union rep and the store mgr who both tell him they know nothing and the decision will come from HR whenever it comes! What can he do, if anything? I don't have a copy of his contract but can try to obtain one. Does he need legal representation?