This is from Sir Tom’s website:

“He is suffering from vocal chord stress related to the residual effects of a bout of severe viral bronchitis that forced the cancellation of 2 shows in Canada last week. His specialist doctor in NY ordered complete vocal rest to avoid the possibility of any further damage to the chords.”

If you purchased your tickets with a credit card, your card will be credited with your refund. If tickets were purchased by check, cash, or gift certificate, you will receive a refund check. Refunds will be processed over the next three weeks.

Please direct additional questions to Ticket Services at (703) 255-1868. 
For more information, please visit Tom Jones website